Resin composition, preparation method thereof and prepreg

Abstract

The invention provides a resin composition, a preparation method thereof and a prepreg. The resin composition comprises the following components in parts by weight: 40-75 parts of an epoxy resin prepolymer mixture, 4-20 parts of a first thermoplastic toughening agent, 7-20 parts of a second thermoplastic toughening agent and 11-42 parts of a curing agent. According to the resin composition provided by the invention, the fluidity can be controlled in the heating curing process, and aggregation at the R corner of a composite material structural member is avoided.

Description

Technical Field

[0001] This disclosure relates to the field of composite material technology, and in particular to a resin composition and its preparation method, as well as a prepreg. Background Technology

[0002] Thermoplastic toughened epoxy resin-based carbon fiber composites are widely used in high-end fields such as aerospace, where the demand for products with high strength, high modulus, and high toughness is increasingly evident. However, epoxy resin does not possess good crack resistance and toughness, so thermoplastic toughening agents are often added to epoxy resin to meet mechanical requirements. Summary of the Invention

[0003] To address the problems existing in the related technologies, this disclosure provides a resin composition, its preparation method, and a prepreg.

[0004] According to a first aspect of the present disclosure, a resin composition is provided, the resin composition comprising the following components, the content of each component being expressed by weight as follows: 40-75 parts of epoxy resin prepolymer mixture. 4-20 parts of the first thermoplastic toughening agent, 7-20 parts of the second thermoplastic toughening agent, 11-42 parts of curing agent.

[0005] In some embodiments of this disclosure, the mass ratio of the epoxy resin prepolymer mixture to the sum of the first thermoplastic toughening agent and the second thermoplastic toughening agent is (1.8~6.1):1.

[0006] In some embodiments of this disclosure, the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is (0.52~2.33):1.

[0007] In some embodiments of this disclosure, the second thermoplastic toughening agent has a core-shell structure, the core of the second thermoplastic toughening agent is polyamide, and the outer shell of the second thermoplastic toughening agent is epoxy resin and curing agent; wherein, the mass ratio of the polyamide, the epoxy resin and the curing agent is 1:(0.3~0.6):(0.02~0.08).

[0008] In some embodiments of this disclosure, the D50 particle size of the second thermoplastic toughening agent is 8-30 micrometers.

[0009] In some embodiments of this disclosure, the first thermoplastic toughening agent includes at least one of polysulfone, polyethersulfone, polyimide, and polyetheretherketone.

[0010] In some embodiments of this disclosure, the epoxy resin prepolymer mixture includes at least two of bisphenol A type epoxy resin, bisphenol F epoxy resin, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin.

[0011] According to a second aspect of the present disclosure, a method for preparing a resin composition is provided, the method being used to prepare the resin composition as described above; the method comprising: The epoxy resin prepolymer mixture and the first thermoplastic toughening agent are dispersed under the first preset conditions to obtain the first mixed system; A second thermoplastic toughening agent is added to the first mixture and dispersed under a second preset condition to obtain a second mixture. The curing agent is added to the second mixing system and dispersed under the third preset conditions to obtain a resin composition.

[0012] In some embodiments of this disclosure, the first preset condition includes: Disperse at 50~100℃ for 20~40 min, then raise the temperature to 140~170℃ and hold for 60~120 min; The second preset condition includes: Disperse at 50~100℃ for 40~80 min; The third preset condition includes: Disperse at 50~90℃ for 40~80 minutes.

[0013] According to a third aspect of the present disclosure, a prepreg is provided, the prepreg comprising a resin composition as described above, or a resin composition prepared by a method comprising the resin composition as described above.

[0014] The beneficial effects of this disclosure include, but are not limited to: 40-75 parts of the epoxy resin prepolymer mixture in the resin composition provided by this disclosure ensure the initial viscosity of the resin composition and reduce its flowability. 4-20 parts of the first thermoplastic toughening agent can ensure toughening and tackifying effects while preventing the viscosity of the resin composition from becoming too high. 7-20 parts of the second thermoplastic toughening agent has a core-shell structure and can chemically react with the epoxy resin prepolymer mixture during the curing process to form chemical bonds, hindering the flow of the resin composition, changing its rheological properties, causing the viscosity to rise prematurely, and reducing its flowability. 11-42 parts of curing agent ensure sufficient curing agent to initiate the crosslinking reaction and form a crosslinking network, inhibiting the flow of the resin composition. Therefore, with the above components and their contents, the resin composition provided by this disclosure can achieve controllable flowability during the curing process and avoid aggregation at the R-corners of the composite structure.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of these embodiments. In these drawings, similar reference numerals are used to denote similar elements. The drawings described below are some embodiments of the present disclosure, but not all embodiments. Other drawings will be readily available to those skilled in the art based on these drawings without inventive effort.

[0017] Figure 1 This is a schematic flowchart of a method for preparing a resin composition according to an exemplary embodiment of the present disclosure; Figure 2 This is a schematic diagram of the shear viscosity temperature scan curves of the resin composition in Comparative Example 1 and Example 1. Figure 3 Metallographic micrograph of the R-angle of the composite structural component prepared by the resin composition of Example 1 of this disclosure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this disclosure can be arbitrarily combined with each other.

[0019] Currently, the mainstream high-temperature aerospace prepreg resin formulations in China adopt a formulation system of various epoxy resin prepolymers + thermoplastic toughening agents. This system has good mechanical properties, but it exposes the problem of uncontrollable prepreg flow. Without adding any auxiliary means, the thickness of the R-corner of the molded composite structural parts often exceeds the control requirements. This is mainly because the resin viscosity is low and the resin flow is large during the curing process.

[0020] Based on this, the present disclosure provides a resin composition in which 40-75 parts of an epoxy resin prepolymer mixture ensure the initial viscosity of the resin composition and reduce its flowability. 4-20 parts of a first thermoplastic toughening agent ensure toughening and tackifying effects while preventing excessively high viscosity of the resin composition. 7-20 parts of a second thermoplastic toughening agent with a core-shell structure can chemically react with the epoxy resin prepolymer mixture during curing to form chemical bonds, hindering the flow of the resin composition, altering its rheological properties, causing premature viscosity increase, and reducing flowability. 11-42 parts of a curing agent ensure sufficient curing agent to initiate a crosslinking reaction to form a crosslinked network, inhibiting the flow of the resin composition. Therefore, with the above components and their contents, the resin composition provided by the present disclosure can achieve controllable flowability during curing and avoid aggregation at the R-corners of composite structural parts.

[0021] An exemplary embodiment of this disclosure provides a resin composition comprising the following components, the contents of which are expressed by weight as follows: 40-75 parts of epoxy resin prepolymer mixture. 4-20 parts of the first thermoplastic toughening agent, 7-20 parts of the second thermoplastic toughening agent, 11-42 parts of curing agent.

[0022] In the resin composition provided in this embodiment, the epoxy resin prepolymer mixture is the uncured epoxy resin mixture. The epoxy resin prepolymer mixture is the primary factor in controlling the viscosity of the resin composition. In this embodiment, controlling the weight parts of the epoxy resin prepolymer mixture to 40-75 parts can ensure the initial viscosity of the resin composition and reduce its flowability. For example, the weight parts of the epoxy resin prepolymer mixture can be 40, 60, or 75 parts, or any value between the exemplary weight parts, such as any value between 50 and 65 parts.

[0023] In the resin composition provided in this embodiment, the first thermoplastic toughening agent can toughen the resin composition and increase its viscosity and reduce its flowability through friction. In this embodiment, the weight percentage of the first thermoplastic toughening agent is controlled between 4 and 20 parts. This ensures both toughening and thickening effects while avoiding excessively high viscosity of the resin composition and the agglomeration of the first thermoplastic toughening agent within the resin composition. For example, the weight percentage of the first thermoplastic toughening agent can be 4, 10, or 20 parts, or any value between the exemplary weight percentages, such as 8 to 15 parts.

[0024] In the resin composition provided in this embodiment, the second thermoplastic toughening agent has a core-shell structure, which can chemically react with the epoxy resin prepolymer mixture during the curing process to form chemical bonds, hindering the flow of the resin composition, changing the rheological properties of the resin composition, increasing viscosity prematurely, and reducing fluidity. In this embodiment, the weight percentage of the second thermoplastic toughening agent is controlled between 7 and 20 parts, which can ensure the thickening effect while avoiding excessively high viscosity of the resin composition and the problem of agglomeration of the second thermoplastic toughening agent in the resin composition. For example, the weight percentage of the second thermoplastic toughening agent can be 7, 12, or 20 parts, or any value between the exemplary weight percentages, such as any value between 10 and 15 parts.

[0025] In the resin composition provided in this embodiment, the curing agent is used to initiate the crosslinking reaction of the epoxy resin prepolymer mixture during the temperature curing process. In this embodiment, controlling the weight of the curing agent to be between 11 and 42 parts ensures sufficient curing agent to initiate the crosslinking reaction and form a crosslinked network, thus inhibiting the flow of the resin composition. For example, the weight of the curing agent can be 11, 30, or 42 parts, or any value between the exemplary weights, such as any value between 20 and 30 parts. Exemplarily, the curing agent can be at least one of anhydride, aromatic amine, polyol, methylguanidine, aromatic, aliphatic amine, acid anhydride, Lewis acid-substituted urea, imidazole, and hydrazine. For example, the curing agent can be diaminodiphenyl sulfone.

[0026] In the resin composition provided in this embodiment, 40-75 parts of epoxy resin prepolymer mixture ensure the initial viscosity of the resin composition and reduce its flowability. 4-20 parts of a first thermoplastic toughening agent ensure toughening and tackifying effects while preventing excessively high viscosity. 7-20 parts of a second thermoplastic toughening agent with a core-shell structure react chemically with the epoxy resin prepolymer mixture during curing to form chemical bonds, hindering the flow of the resin composition, altering its rheological properties, causing premature viscosity increases, and reducing flowability. 11-42 parts of curing agent ensure sufficient curing agent to initiate crosslinking reactions and form a crosslinked network, inhibiting the flow of the resin composition. Therefore, with the above components and their contents, the resin composition provided in this embodiment achieves controllable flowability during curing and avoids aggregation at the R-corners of the composite structure.

[0027] In one exemplary embodiment, the mass ratio of the epoxy resin prepolymer mixture to the sum of the first thermoplastic toughening agent and the second thermoplastic toughening agent is (1.8~6.1):1.

[0028] The epoxy resin prepolymer mixture is the uncured epoxy resin mixture. It is the primary factor controlling the viscosity of the resin composition, ensuring its initial viscosity. The first thermoplastic toughening agent toughens the resin composition and increases its viscosity through friction, reducing its flowability. The second thermoplastic toughening agent has a core-shell structure and reacts chemically with the epoxy resin prepolymer mixture during curing, forming chemical bonds that hinder the flow of the resin composition, altering its rheological properties, causing a premature increase in viscosity, and reducing its flowability. In this embodiment, the mass ratio of the epoxy resin prepolymer mixture to the sum of the first and second thermoplastic toughening agents is controlled at (1.8~6.1):1. This ensures controllable flowability of the resin composition during curing and prevents agglomeration of the first and second thermoplastic toughening agents in the epoxy resin prepolymer mixture. For example, the mass ratio of the epoxy resin prepolymer mixture to the sum of the first thermoplastic toughening agent and the second thermoplastic toughening agent can be 1.8:1, 3.5:1, or 6.1:1. The mass ratio of the epoxy resin prepolymer mixture to the sum of the first thermoplastic toughening agent and the second thermoplastic toughening agent can also be any value between the exemplary mass ratios, such as any value between (2.5~5.5):1.

[0029] In one exemplary embodiment, the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is (0.52~2.33):1.

[0030] In this embodiment, the first thermoplastic toughening agent can improve the toughness of the prepreg through plastic deformation and increase the viscosity of the resin composition through friction. The core-shell structure of the second thermoplastic toughening agent induces shear yielding, improving the toughness of the prepreg, and reacts chemically with the epoxy resin prepolymer mixture during the curing process to form chemical bonds, thereby increasing the viscosity of the resin composition. When the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is too high, i.e., there is too much of the first thermoplastic toughening agent, it may cause agglomeration of the first thermoplastic toughening agent in the resin composition. Conversely, when the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is too low, i.e., there is too much of the second thermoplastic toughening agent, it may lead to excessively high viscosity of the resin composition, affecting the wettability of the resin composition to the fibers. Therefore, in this embodiment, the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is controlled to be (0.52~2.33):1. For example, the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent can be 0.52:1, 1.50:1, or 2.33:1. The mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent can also be any value between the exemplary mass ratios, for example, the mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent can be any value between (0.80~2.15):1.

[0031] In an exemplary embodiment, the second thermoplastic toughening agent has a core-shell structure, with the core of the second thermoplastic toughening agent being polyamide and the outer shell being epoxy resin and curing agent; wherein the mass ratio of polyamide, epoxy resin and curing agent is 1:(0.3~0.6):(0.02~0.08).

[0032] The second thermoplastic toughening agent has a core-shell structure. The core of the second thermoplastic toughening agent is polyamide, and the outer shell consists of epoxy resin and a curing agent. That is, the second thermoplastic toughening agent uses polyamide as its core, with epoxy resin and a curing agent coated on its surface. The curing agent in the outer shell can graft the epoxy resin from the outer shell onto the polyamide core, forming a stable core-shell structure. The epoxy resin in the outer shell is compatible with the epoxy resin prepolymer in the resin composition, thus improving the compatibility between the second thermoplastic toughening agent and the epoxy resin prepolymer. During the prepreg preparation process, when temperature curing occurs, the polyamide in the second thermoplastic toughening agent can chemically react with the epoxy resin prepolymer mixture in the resin composition, forming chemical bonds that hinder the flow of the resin composition, altering its rheological properties, causing a premature increase in viscosity, and a decrease in fluidity. In this process, the chemical reaction between the polyamide and epoxy resin prepolymer mixture occurs between the layers. This reaction promotes the support of the polyamide for the interlayer of the prepreg, preventing aggregation and irregular interlayer morphology caused by fiber slippage, which would otherwise lead to excessive thickness in the R-zone of the composite structure. Furthermore, the toughening properties of the polyamide itself in the interlayer remain unchanged, thus having minimal impact on the mechanical properties of the prepreg. In this embodiment, the mass ratio of polyamide, epoxy resin, and curing agent is limited to 1:(0.3~0.6):(0.02~0.08), which ensures the stability of the core-shell structure of the second thermoplastic toughening agent and its viscosity-enhancing effect on the resin composition. For example, the mass ratio of polyamide, epoxy resin and curing agent can be 1:0.3:0.02, 1:0.5:0.05 or 1:0.6:0.08. The mass ratio of polyamide, epoxy resin and curing agent can also be any value between the exemplary mass ratios, such as any value between 1:(0.4~0.5):(0.03~0.06).

[0033] In one exemplary embodiment, the D50 particle size of the second thermoplastic toughening agent is 8 to 30 micrometers.

[0034] A high D50 particle size of the second thermoplastic toughening agent reduces the shear and face shear strength of the prepreg, while a low D50 particle size results in a high specific surface area, making uniform dispersion between layers difficult. In this embodiment, controlling the D50 particle size of the second thermoplastic toughening agent to 8-30 micrometers ensures uniform dispersion of the second thermoplastic toughening agent in the resin composition. This results in excellent interfacial properties of the second thermoplastic toughening agent between prepreg layers and improves the toughness of the resin composition. Simultaneously, it hinders the flow of the resin composition, preventing excessive thickness tolerances in the R-zone of the composite structure. For example, the D50 particle size of the second thermoplastic toughening agent can be 8 micrometers, 20 micrometers, or 30 micrometers. It can also be any value within the exemplary particle size range, such as any value between 10 and 25 micrometers.

[0035] In one exemplary embodiment, the first thermoplastic toughening agent includes at least one of polysulfone, polyethersulfone, polyimide, and polyetheretherketone.

[0036] Polysulfone, polyethersulfone, polyimide, and polyetheretherketone are all thermoplastic materials with high temperature resistance, high strength, and high modulus. Using at least one of these as a first thermoplastic toughening agent can improve the toughness of the prepreg through plastic deformation, increase the viscosity of the resin composition through friction, hinder the flow of the resin composition during the curing process, and prevent the thickness of the R-zone of the composite structure from exceeding tolerances.

[0037] In one exemplary embodiment, the epoxy resin prepolymer mixture includes at least two of bisphenol A type epoxy resin, bisphenol F epoxy resin, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin.

[0038] In this embodiment, at least two of the following are selected: bisphenol A type epoxy resin, bisphenol F epoxy resin, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin. For example, two, three, or four of these resins are selected to form an epoxy resin prepolymer mixture. Resins with different crosslinking densities and mechanical properties can be achieved using epoxy resins with different functionalities and reactivity. Using an epoxy resin prepolymer mixture provides a more diverse and balanced range of properties compared to using a single type of epoxy resin.

[0039] An exemplary embodiment of this disclosure provides a method for preparing a resin composition as described above. Figure 1 As shown, the preparation method includes: S100. The epoxy resin prepolymer mixture and the first thermoplastic toughening agent are dispersed under the first preset conditions to obtain the first mixed system.

[0040] S200. The second thermoplastic toughening agent is added to the first mixture system and dispersed under the second preset conditions to obtain the second mixture system.

[0041] S300. Add the curing agent to the second mixing system and disperse it under the third preset conditions to obtain a resin composition.

[0042] In the preparation method of the resin composition provided in this embodiment, the first thermoplastic toughening agent, the second thermoplastic toughening agent, and the curing agent are dispersed in the epoxy resin prepolymer mixture in sequence and stepwise. This can avoid the problems of aggregation and dispersion difficulties caused by simultaneous addition, and is conducive to the uniform dispersion of each component, forming a uniform and stable resin composition.

[0043] In an exemplary embodiment, the first preset conditions include: dispersing at a temperature of 50~100°C for 20~40 minutes, and then raising the temperature to 140~170°C and holding at that temperature for 60~120 minutes.

[0044] In this embodiment, the epoxy resin prepolymer mixture and the first thermoplastic toughening agent are dispersed at a temperature of 50-100°C for 20-40 minutes. During this process, the first thermoplastic toughening agent softens, and the epoxy resin prepolymer mixture initially wets the surface of the first thermoplastic toughening agent. Then, the temperature is raised to 140-170°C and held for 60-120 minutes. During this process, the first thermoplastic toughening agent is completely dispersed in the epoxy resin prepolymer mixture. For example, the dispersion temperature can be 50°C, 80°C, or 100°C, or any value between these exemplary temperatures, such as any value between 60-80°C. For example, the dispersion time can be 20 minutes, 30 minutes, or 40 minutes, or any value between these exemplary times, such as any value between 25-35 minutes. For example, the insulation temperature can be 140℃, 160℃, or 170℃, or any value between the exemplary temperatures, such as any value between 150℃ and 160℃. Similarly, the insulation duration can be 60 minutes, 100 minutes, or 120 minutes, or any value between the exemplary durations, such as any value between 80 and 100 minutes.

[0045] In one exemplary embodiment, the second preset condition includes: dispersion at a temperature of 50~100°C for 40~80 minutes.

[0046] After dispersing and maintaining the first thermoplastic toughening agent in the epoxy resin prepolymer mixture at a certain temperature, the temperature of the first mixture is cooled to 50-100°C. The second thermoplastic toughening agent is then added to the first mixture and dispersed at 50-100°C for 40-80 minutes to obtain the second mixture. Maintaining a temperature of 50-100°C ensures sufficient fluidity in the first mixture to disperse the second thermoplastic toughening agent while avoiding damage to the core-shell structure of the second thermoplastic toughening agent from excessively high dispersion temperatures. For example, the dispersion temperature can be 50°C, 80°C, or 100°C, or any value between these exemplary temperatures, such as any value between 60-80°C. Similarly, the dispersion time can be 40 minutes, 60 minutes, or 80 minutes, or any value between these exemplary times, such as any value between 50-70 minutes.

[0047] In one exemplary embodiment, the third preset condition includes: dispersion at a temperature of 50~90°C for 40~80 minutes.

[0048] The curing agent is added to the second mixing system and dispersed at a temperature of 50-90°C for 40-80 minutes to obtain a resin composition. The dispersion temperature of 50-90°C ensures that the second mixing system has sufficient fluidity to disperse the curing agent, while being well below the curing reaction temperature to prevent premature curing of the resin composition. For example, the dispersion temperature can be 50°C, 80°C, or 90°C, or any value between these exemplary temperatures, such as any value between 60-80°C. Similarly, the dispersion time can be 40 minutes, 60 minutes, or 80 minutes, or any value between these exemplary times, such as any value between 50-70 minutes.

[0049] In an exemplary embodiment, the method for preparing the resin composition further includes preparing a second thermoplastic toughening agent: 25-35 kg of N-methyl-2-pyrrolidone is weighed and placed in a container, heated to 25-35°C and stirred until homogeneous. Following a mass ratio of polyamide, epoxy resin, and curing agent of 1:(0.3-0.6):(0.02-0.08), polyamide is first added to N-methyl-2-pyrrolidone, followed by epoxy resin and curing agent, and stirred to form a first dispersion system. Nitrogen gas is introduced into the container containing the first dispersion system to replace 95-99% of the gas in the container. 43 kg of a polyvinyl alcohol solution composed of 3 kg of polyvinyl alcohol and 40 kg of deionized water is weighed and added dropwise to the first dispersion system at a rate of 0.2-0.4 kg / min, stirred until the first dispersion system presents a homogeneous milky white emulsion, thus obtaining the second dispersion system. The second dispersion system was distilled under a vacuum of -0.09 MPa for 8 hours to remove organic solvents. The resulting slurry was washed with water, classified, and subjected to particle size classification. It was then rinsed and diluted with hot water at 65°C. After solid-liquid separation, drying, and pulverization, the second thermoplastic toughening agent was obtained from the sieved intermediate.

[0050] An exemplary embodiment of this disclosure provides a prepreg comprising a resin composition as described above, or a resin composition prepared by a method comprising the resin composition as described above. The prepreg provided in this embodiment contains a resin composition with high viscosity and controllable flowability, which can prevent the resin composition from agglomerating at the radius (R) corners of the composite structure during the temperature curing process.

[0051] To more clearly explain the technical solutions and beneficial effects provided by the exemplary embodiments of this disclosure, the component content and performance parameters of the resin compositions and prepregs of Exemplary Embodiments 1 to 9 and Comparative Example 1 are given.

[0052] The resin compositions of Examples 1-9 and Comparative Example 1 were prepared according to the following method: The epoxy resin prepolymer mixture and the first thermoplastic toughening agent are dispersed at a temperature of 50~100℃ for 20~40 min, and then the temperature is raised to 140~170℃ and held for 60~120 min to obtain the first mixed system.

[0053] The temperature of the first mixture is cooled to 50~100℃, and the second thermoplastic toughening agent is added to the first mixture. The mixture is then dispersed at 50~100℃ for 40~80 minutes to obtain the second mixture.

[0054] The curing agent was added to the second mixing system and dispersed at 50-90°C for 40-80 minutes to obtain the resin composition. The content of each component in the resin composition is shown in Table 1.

[0055] The resin composition is dry impregnated in the form of a film to obtain a prepreg.

[0056] The performance of the resin compositions and prepregs of Examples 1-9 and Comparative Example 1 were tested according to the following method, and the test results are recorded in Table 1.

[0057] 1. Viscosity test of resin composition The shear viscosity of the resin composition was tested on a spin-on rheometer at a heating rate of 4℃ / min. The rheological properties of the resin composition were analyzed by comparing the changes in minimum viscosity at 85℃ and the temperature corresponding to the minimum viscosity.

[0058] 2. Prepreg Flowability Test Four samples with an area of ​​(100±1) mm × (100±1) mm were cut and laid up sequentially at 0°, 90°, 90°, and 0°. The flow properties were measured at 180℃±5℃ and 690 kPa. The holding time was 25 min. The weight change of the prepreg before and after hot pressing was recorded, and the flowability of the prepreg was calculated.

[0059] 3. Mechanical property testing Prepregs were cured in autoclaves at 180℃ for 2 hours under standard curing regime (heating rate set at 2-3℃ / min) to obtain composite laminates for mechanical testing. The tensile strength, compressive strength, impact strength (compressive strength after impact), laminate shear strength, and face shear strength of the composite laminates under standard curing regime were tested.

[0060] Table 1

[0061] As shown in Table 1, compared to Comparative Example 1, the overall viscosity and minimum viscosity of the resin compositions and prepregs in Examples 1-9 are increased, and the temperature corresponding to the minimum viscosity is decreased, indicating that the fluidity of the resin compositions is reduced and the mechanical properties are improved. Figure 2 The diagram shows the shear viscosity temperature scan curve 10 of the resin composition of Comparative Example 1 and the shear viscosity temperature scan curve 20 of the resin composition of Example 1. Figure 2 The horizontal axis represents temperature in °C, and the vertical axis represents shear viscosity in Pa·s. It can be seen that the addition of the second thermoplastic toughening agent changed the viscosity and rheological properties of the resin composition. Figure 3The image shows a metallographic micrograph of the R-angle of the composite structure prepared by the resin composition of Example 1. It can be seen that the interlayer thickness is uniform, the fibers are neatly arranged, and there are no obvious fiber aggregation and wrinkle defects.

[0062] The above-described contents can be implemented individually or in various combinations, and all such variations are within the scope of this disclosure.

[0063] Finally, it should be noted that in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A resin composition, characterized in that, The resin composition comprises the following components, the content of which is expressed by weight as follows: 40-75 parts of epoxy resin prepolymer mixture. 4-20 parts of the first thermoplastic toughening agent, 7-20 parts of the second thermoplastic toughening agent, 11-42 parts of curing agent.

2. The resin composition according to claim 1, characterized in that, The mass ratio of the epoxy resin prepolymer mixture to the sum of the first thermoplastic toughening agent and the second thermoplastic toughening agent is (1.8~6.1):

1.

3. The resin composition according to claim 1, characterized in that, The mass ratio of the first thermoplastic toughening agent to the second thermoplastic toughening agent is (0.52~2.33):

1.

4. The resin composition according to claim 1, characterized in that, The second thermoplastic toughening agent has a core-shell structure. The core of the second thermoplastic toughening agent is polyamide, and the outer shell of the second thermoplastic toughening agent is epoxy resin and curing agent. The mass ratio of the polyamide, the epoxy resin and the curing agent is 1:(0.3~0.6):(0.02~0.08).

5. The resin composition according to claim 1 or 4, characterized in that, The D50 particle size of the second thermoplastic toughening agent is 8~30 micrometers.

6. The resin composition according to claim 1, characterized in that, The first thermoplastic toughening agent includes at least one of polysulfone, polyethersulfone, polyimide, and polyetheretherketone.

7. The resin composition according to claim 1, characterized in that, The epoxy resin prepolymer mixture includes at least two of the following: bisphenol A type epoxy resin, bisphenol F epoxy resin, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin.

8. A method for preparing a resin composition, characterized in that, The preparation method is used to prepare the resin composition according to any one of claims 1 to 7; the preparation method includes: The epoxy resin prepolymer mixture and the first thermoplastic toughening agent are dispersed under the first preset conditions to obtain the first mixed system; A second thermoplastic toughening agent is added to the first mixture and dispersed under a second preset condition to obtain a second mixture. The curing agent is added to the second mixing system and dispersed under the third preset conditions to obtain a resin composition.

9. The method for preparing the resin composition according to claim 8, characterized in that, The first preset conditions include: Disperse at 50~100℃ for 20~40 min, then raise the temperature to 140~170℃ and hold for 60~120 min; The second preset condition includes: Disperse at 50~100℃ for 40~80 min; The third preset condition includes: Disperse at 50~90℃ for 40~80 minutes.

10. A prepreg, characterized in that, The prepreg comprises the resin composition as described in any one of claims 1 to 7, or a resin composition prepared by a method comprising the resin composition as described in any one of claims 8 to 9.

Images