Toughened epoxy resin composition, prepreg and composite material

Abstract

The invention discloses a toughened epoxy resin composition, and relates to the technical field of high polymer materials. The toughened epoxy resin composition comprises the following components in parts by weight: 100-120 parts of an epoxy resin mixture; 4-15 parts by weight of thermoplastic toughening resin; 10-20 parts by weight of a curing agent; the epoxy resin mixture comprises liquid epoxy resin and solid epoxy resin in a preset weight ratio. The toughened epoxy resin composition provided by the invention has good toughness, and a composite material prepared from the toughened epoxy resin composition provided by the invention has the advantages of excellent impact resistance and good processing property.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a toughened epoxy resin composition, prepreg and composite material. BACKGROUND

[0002] The development of carbon fiber composite industry promotes the development of many fields such as energy, military, transportation and sports. Among them, the thermosetting resin matrix composite material has been widely used due to its excellent comprehensive performance. However, during the curing process of thermosetting resin, the molecular chains form a highly cross-linked three-dimensional network structure through chemical bonds, which limits the movement between molecular chains, reduces the flexibility of the material, increases the brittleness, and reduces the service life of the product. SUMMARY

[0003] In order to solve the above technical problems, the present application aims to provide a toughened epoxy resin composition, prepreg and composite material. The composite material prepared by the toughened epoxy resin composition has the advantages of excellent impact resistance and good process performance.

[0004] According to a first aspect of the present application, a toughened epoxy resin composition is provided, which comprises the following components by weight:

[0005] epoxy resin mixture 100-120 parts by weight;

[0006] thermoplastic toughening resin 4-15 parts by weight;

[0007] curing agent 10-20 parts by weight;

[0008] The epoxy resin mixture comprises a liquid epoxy resin and a solid epoxy resin in a predetermined weight ratio.

[0009] In some embodiments of the present application, the predetermined weight ratio is 0.67-1.18:1.

[0010] In some embodiments of the present application, the liquid epoxy resin comprises one or more of bisphenol A type liquid epoxy resin, bisphenol F type liquid epoxy resin; and / or

[0011] The solid epoxy resin comprises one or more of bisphenol A type solid epoxy resin, bisphenol F type solid epoxy resin, and phenolic epoxy resin.

[0012] In some embodiments of the present application, when the liquid epoxy resin comprises bisphenol A type liquid epoxy resin and bisphenol F type liquid epoxy resin, the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin and the thermoplastic toughening resin is 2.50-5.00:1.67-5.00:1.

[0013] In some embodiments of the present application, when the solid epoxy resin comprises bisphenol A type solid epoxy resin and phenolic epoxy resin, the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin is 1.00-4.00:1;

[0014] When the solid epoxy resin comprises bisphenol F type epoxy resin and phenolic epoxy resin, the weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin is 1.07-2.24:1.

[0015] In some embodiments of the present application, the thermoplastic toughening resin comprises one or more of polyphenol epoxy resin, polyether sulfone resin, polyamide resin, polyphenyl ether resin, and polysulfone resin; and / or

[0016] The curing agent comprises dicyandiamide.

[0017] In some embodiments of the present application, the toughened epoxy resin composition further comprises 1-5 parts by weight of an accelerator.

[0018] In some embodiments of the present application, the accelerator comprises one or more of 2-methylimidazole, 3-phenyl-1,1-dimethylurea, and triphenylphosphine.

[0019] According to a second aspect of the present application, a prepreg is provided, the prepreg comprising the toughened epoxy resin composition according to any one of the above.

[0020] According to a third aspect of the present application, a composite material is provided, the composite material being cured from the prepreg according to the above, the curing temperature being 120-150℃, and the curing time being 30-60min.

[0021] The technical solutions provided by the present application can have the following beneficial effects:

[0022] The present application can improve the strength and impact resistance of the material by mixing the thermoplastic toughening resin with the epoxy resin mixture, and can improve the process performance of the material by compounding the liquid epoxy resin and the solid epoxy resin.

[0023] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0025] Figure 1 is a viscosity-temperature curve graph of Example 1. DETAILED DESCRIPTION

[0026] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application and the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application. It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other at will.

[0027] In order to improve the flexibility of the epoxy resin system, various toughening technologies such as intrinsic resin modification toughening, thermoplastic rubber toughening, thermoplastic resin toughening and nanoparticle toughening can be used. However, in the actual production process, in addition to considering the mechanical properties of the material, the molding process of the material also has an important influence on the product weight, cost, production efficiency and the like. At present, the epoxy resin-based composite material is mainly prepared by using the prepreg process. The prepreg is a key intermediate for the preparation of composite materials, which is made of a resin matrix impregnated with reinforcing fibers (such as carbon fibers, glass fibers, etc.), and has excellent mechanical properties and process adaptability. At present, the main preparation processes of the prepreg include hot melt method, solution impregnation method, powder impregnation method, film lamination method and the like. Among them, the hot melt method is to heat and melt the resin into a flowing state, and then make the fiber pass through the molten resin, under the action of a certain pressure and temperature, the resin penetrates the fiber and fills the gap between the fibers, and the prepreg is obtained after cooling.

[0028] When the prepreg is prepared by using the hot melt method, the content of the resin can be accurately controlled, and the use of organic solvents can be reduced, which meets the environmental protection requirements. However, the hot melt method has certain requirements for the viscosity and wettability of the resin. After the toughening agent and other components are added to the epoxy resin system, due to the increase of the intermolecular force and the internal resistance of the system, the viscosity of the system will increase, which will affect the process performance of the material.

[0029] Based on this, the present application provides a toughened epoxy resin composition, which comprises the following components by weight: 100-120 parts by weight of an epoxy resin mixture; 4-15 parts by weight of a thermoplastic toughening resin; and 10-20 parts by weight of a curing agent. The epoxy resin mixture comprises a liquid epoxy resin and a solid epoxy resin in a predetermined weight ratio. By matching the thermoplastic toughening resin with the epoxy resin mixture, the strength and impact resistance of the material can be improved, and by compounding the liquid epoxy resin and the solid epoxy resin, the process performance of the material can be improved.

[0030] Some specific embodiments described below are intended to facilitate the understanding of the present embodiments by those skilled in the art, and the present embodiments are not limited to some specific embodiments described below.

[0031] An exemplary embodiment of the present application provides a toughened epoxy resin composition, which comprises the following components by weight:

[0032] an epoxy resin mixture 100-120 parts by weight;

[0033] a thermoplastic toughening resin 4-15 parts by weight;

[0034] a curing agent 10-20 parts by weight;

[0035] The epoxy resin mixture comprises liquid epoxy resin and solid epoxy resin in a preset weight ratio.

[0036] In the embodiment, the thermoplastic toughening resin is dissolved in the epoxy resin system, and during the curing process, the molecular chains of the thermoplastic resin and the epoxy resin interpenetrate and entangle each other to form a semi-interpenetrating network structure. On the one hand, the semi-interpenetrating network structure can limit the movement of the molecular chains of the epoxy resin, thereby improving the heat resistance and modulus of the epoxy resin; on the other hand, when subjected to external force, the semi-interpenetrating network structure can absorb energy through the slippage and deformation of the molecular chains, thereby improving the toughness and impact resistance of the epoxy resin.

[0037] In addition, the epoxy resin mixture comprises liquid epoxy resin and solid epoxy resin. The liquid epoxy resin has the advantages of good flowability, low curing shrinkage, and strong adhesion, and is suitable for impregnating the reinforcing fibers; however, the curing time of the liquid epoxy resin is relatively long, and the impact resistance of the cured epoxy resin is relatively low and the brittleness is relatively large. The solid epoxy resin has the advantages of high hardness, good wear resistance, and strong adhesion; however, the flowability of the solid epoxy resin is low, and the impact resistance of the cured epoxy resin is relatively low and the brittleness is relatively large. Therefore, in the embodiment, the liquid epoxy resin and the solid epoxy resin are compounded in a preset weight ratio, which can improve the process performance of the prepreg prepared from the toughened epoxy resin composition and improve the mechanical strength of the composite material prepared from the prepreg. In addition, the thermoplastic toughening resin can serve as a toughening component to compensate for the defect of the large brittleness of the epoxy resin mixture, thereby improving the impact resistance of the composite material.

[0038] Exemplarily, in an embodiment, the toughened epoxy resin composition comprises the following components by weight:

[0039] an epoxy resin mixture 100 parts by weight;

[0040] a thermoplastic toughening resin 4 parts by weight;

[0041] a curing agent 10 parts by weight;

[0042] The epoxy resin mixture comprises liquid epoxy resin and solid epoxy resin in a preset weight ratio.

[0043] In another embodiment, the toughened epoxy resin composition comprises the following components in parts by weight:

[0044] epoxy resin mixture 110 parts by weight;

[0045] thermoplastic toughening resin 8 parts by weight;

[0046] curing agent 14 parts by weight;

[0047] The epoxy resin mixture comprises a predetermined weight ratio of liquid epoxy resin and solid epoxy resin.

[0048] In another embodiment, the toughened epoxy resin composition comprises the following components in parts by weight:

[0049] epoxy resin mixture 100 parts by weight;

[0050] thermoplastic toughening resin 12 parts by weight;

[0051] curing agent 17 parts by weight;

[0052] The epoxy resin mixture comprises a predetermined weight ratio of liquid epoxy resin and solid epoxy resin.

[0053] In another embodiment, the toughened epoxy resin composition comprises the following components in parts by weight:

[0054] epoxy resin mixture 120 parts by weight;

[0055] thermoplastic toughening resin 15 parts by weight;

[0056] curing agent 20 parts by weight;

[0057] The epoxy resin mixture comprises a predetermined weight ratio of liquid epoxy resin and solid epoxy resin.

[0058] In an exemplary embodiment, the predetermined weight ratio is 0.67-1.18:1.

[0059] In this embodiment, by adjusting the weight ratio of liquid epoxy resin and solid epoxy resin, the wettability and viscosity of the toughened epoxy resin composition are adjusted, so as to adjust the mechanical properties of the composite material prepared from the toughened epoxy resin composition.

[0060] Exemplarily, the predetermined weight ratio is 0.67:1, 0.83:1, 0.96:1, 1.08:1, 1.15:1, 1.18:1. The predetermined weight ratio can also be any ratio between the exemplary weight ratios, for example, the predetermined weight ratio can also be any ratio between 0.96-1.15:1.

[0061] In an exemplary embodiment, the liquid epoxy resin comprises one or more of a bisphenol A type liquid epoxy resin, a bisphenol F type liquid epoxy resin.

[0062] The bisphenol A type liquid epoxy resin has the advantages of high bonding strength and good chemical resistance, but has low heat resistance and toughness, large viscosity and low flowability, and relatively poor processability. The bisphenol F type liquid epoxy resin has lower viscosity than the bisphenol A type epoxy resin, has good impregnation of the reinforcing fibers, and has good thermal stability. In the present embodiment, the liquid epoxy resin can be selected from the bisphenol A type liquid epoxy resin or the bisphenol F type liquid epoxy resin, or a combination of the two. The above resins not only have low cost, wide application and good compatibility, but also can solve the problems of poor processability of the prepreg, serious overflow during resin molding, and insufficient fiber impregnation.

[0063] In an exemplary embodiment, the solid epoxy resin comprises one or more of a bisphenol A type solid epoxy resin, a bisphenol F type solid epoxy resin, and a phenolic epoxy resin.

[0064] The bisphenol A type solid epoxy resin has the advantages of high bonding strength, low curing shrinkage, and high mechanical strength, but has low impact resistance and heat resistance. The bisphenol F type epoxy resin has the advantages of low viscosity and good processability, but has low impact resistance and heat resistance. The phenolic epoxy resin has the advantages of high crosslinking density, good heat resistance, and low curing shrinkage, but has high brittleness and is prone to cracking during processing. In the present embodiment, the solid epoxy resin can be selected from one of the bisphenol A type solid epoxy resin, the bisphenol F type solid epoxy resin, and the phenolic epoxy resin, or a combination of two or three of them, to improve the viscosity and processability of the epoxy resin system, and to improve the interfacial properties of the toughened epoxy resin composition and the reinforcing fibers.

[0065] In an exemplary embodiment, when the liquid epoxy resin comprises a bisphenol A type liquid epoxy resin and a bisphenol F type liquid epoxy resin, the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin, and the thermoplastic toughening resin is 2.50-5.00:1.67-5.00:1.

[0066] In the present embodiment, by controlling the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin, and the thermoplastic toughening resin to be 2.50-5.00:1.67-5.00:1, the impact resistance of the cured product of the toughened epoxy resin composition can be improved, and the processability can be improved.

[0067] Exemplarily, the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin, and the thermoplastic toughening resin can be 2.50:1.67:1, 2.50:2.50:1, 3.89:2.68:1, 4.06:4.65:1, 5.00:5.00:1. The weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin, and the thermoplastic toughening resin can also be any ratio between the exemplary weight ratios, for example, the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin, and the thermoplastic toughening resin can also be any ratio between 2.50-4.06:2.50-4.65:1.

[0068] In an exemplary embodiment, when the solid epoxy resin comprises the bisphenol A type solid epoxy resin and the phenolic epoxy resin, the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin is 1.00-4.00:1.

[0069] In this embodiment, by controlling the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin to be 1.0-4.00:1, the toughness and rigidity of the material can be balanced, and the process performance can be improved.

[0070] Exemplarily, the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin can be 1.00:1, 2.56:1, 3.08:1, 3.45:1, 4.00:1. The weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin can also be any ratio between the exemplary weight ratios, for example, the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin can also be any ratio between 2.56-3.45:1.

[0071] In an exemplary embodiment, when the solid epoxy resin comprises the bisphenol F type epoxy resin and the phenolic epoxy resin, the weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin is 1.07-2.24:1.

[0072] In this embodiment, by controlling the weight ratio of the bisphenol F type epoxy resin and the phenolic epoxy resin to be 1.07-2.24:1, the toughness and rigidity of the material can be balanced, and the curing process can be made more stable, reducing the generation of defects, so as to balance production efficiency and product quality.

[0073] Exemplarily, the weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin can be 1.07:1, 1.38:1, 1.89:1, 1.98:1, 2.24:1. The weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin can also be any ratio between the exemplary weight ratios, for example, the weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin can also be any ratio between 1.38-1.98:1.

[0074] In an exemplary embodiment, the thermoplastic toughening resin includes one or more of polyhydroxyether resin, polyether sulfone resin, polyamide resin, polyphenylene ether resin, polysulfone resin.

[0075] Polyhydroxyether resin is a kind of thermoplastic polymer material prepared by polycondensation reaction of bisphenol A (or similar phenolic monomer) and epichlorohydrin, which has excellent impact resistance and bonding performance, and can improve the toughness of the epoxy resin system. Polyether sulfone resin (PES) has high elongation at break, and can effectively prevent crack propagation when the material is subjected to external force, thereby improving the toughness of the epoxy resin system. The flexibility of polyamide resin (PA) can buffer the stress concentration of the material, so that the material has better toughness while maintaining high strength. Polyphenylene oxide resin (PPO) has high elongation at break and impact strength, which can improve the elongation at break and impact strength of the material, and improve the toughness of the epoxy resin system. Polysulfone resin (PSU) has high elongation at break, which can effectively prevent crack propagation when the material is subjected to external force impact, thereby improving the toughness of the epoxy resin system. Among them, the thermoplastic toughening resin can select one of the above thermoplastic toughening resins, or several of them can be compounded. For example, the thermoplastic toughening resin can also include polyether sulfone resin and polyhydroxyether resin in a weight ratio of 1.55-3.10:1.

[0076] In an exemplary embodiment, the curing agent includes dicyandiamide.

[0077] In this embodiment, the curing agent can be dicyandiamide, which has good adaptability with epoxy resin. The epoxy resin cured with dicyandiamide has excellent bonding performance and mechanical properties.

[0078] In an exemplary embodiment, the toughened epoxy resin composition further includes 1-5 parts by weight of an accelerator.

[0079] In this embodiment, by adding the accelerator, the curing temperature of the epoxy resin can be significantly reduced, and the curing time can be shortened. For example, when dicyandiamide is used as the curing agent, the curing temperature is generally 160-180°C, and after adding the accelerator, the curing temperature can be reduced to 120-140°C, and the curing time can be shortened to 30-60 min.

[0080] Exemplarily, the amount of the accelerator in the toughened epoxy resin composition is 1.0 part by weight, 1.5 parts by weight, 2.4 parts by weight, 3.2 parts by weight, or 5.0 parts by weight. The amount of the accelerator in the toughened epoxy resin composition can also be any amount between the exemplified amount values, for example, the amount of the accelerator in the toughened epoxy resin composition can also be any amount between 1.5 parts by weight and 3.2 parts by weight.

[0081] In an exemplary embodiment, the accelerator comprises one or more of 2-methylimidazole, 3-phenyl-1,1-dimethylurea, and triphenylphosphine.

[0082] 2-methylimidazole has high catalytic efficiency, can significantly reduce the curing temperature of the epoxy resin and shorten the curing time, and also has the advantages of small amount, long pot life, and low toxicity. 3-phenyl-1,1-dimethylurea not only can significantly reduce the curing temperature of the epoxy resin and shorten the curing time, but also has good thermal stability at high temperature, so as to improve the mechanical properties and heat resistance of the epoxy resin cured product. As an accelerator, triphenylphosphine can increase the crosslinking density of the epoxy resin, thereby improving the mechanical properties and chemical resistance of the epoxy resin cured product. Among them, the accelerator can select one of the above accelerators, or several of them can be compounded. For example, the accelerator comprises 2-methylimidazole and 3-phenyl-1,1-dimethylurea in a weight ratio of 1.0-2.5:1.

[0083] An exemplary embodiment of the present application provides a prepreg, which comprises the toughened epoxy resin composition according to any one of the above embodiments.

[0084] In the present embodiment, the prepreg comprises the toughened epoxy resin composition, and can further comprise a reinforcing fiber. The toughened epoxy resin composition has good process performance and good wettability to the reinforcing fiber. The reinforcing fiber can be, for example, carbon fiber, which can be, for example, T300-grade carbon fiber, T700-grade carbon fiber, and T800-grade carbon fiber. The weight of the toughened epoxy resin composition can be, for example, 30-45% of the total weight of the prepreg.

[0085] In the preparation of the prepreg, a hot melt method can be used, in which the toughened epoxy resin composition is heated to a molten state, and then a film is formed by a casting or extrusion process. The film is then coated on the reinforcing fiber, and the reinforcing fiber is infiltrated under the action of temperature and pressure. The film coating temperature can be 60-75°C, and the impregnation temperature can be 80-90°C.

[0086] An exemplary embodiment of the present application provides a composite material, which is cured from the prepreg according to the above embodiments, and the curing temperature is 120-150°C and the curing time is 30-60 min.

[0087] In this embodiment, the composite material can be formed by curing the prepreg at a medium temperature. The epoxy resin system cured at a medium temperature has a smaller viscosity at room temperature, which can be suitable for a variety of fillers. For example, the curing temperature can be 120°C, 130°C, 135°C, 142°C, or 150°C. The curing temperature can also be any value between the example values, for example, the curing temperature can also be any value between 130°C and 142°C. The curing time can be 30 minutes, 40 minutes, 48 minutes, 55 minutes, or 60 minutes. For example, the curing time can also be any value between the example values, for example, the curing time can also be any value between 40 minutes and 55 minutes. For example, the prepreg can be cured at a temperature of 130°C for 60 minutes, or at a temperature of 150°C for 30 minutes, to achieve a curing degree of more than 95%.

[0088] The filler includes reinforcing fillers, flame-retardant fillers, heat-conducting fillers, nano fillers, etc. For example, the filler can be silicon dioxide, aluminum oxide, nano calcium carbonate, magnesium hydroxide, etc. For example, the toughened epoxy resin composition can further include 5-15 parts by weight of silicon dioxide.

[0089] In order to more clearly explain the technical solutions of the present application, specific embodiments of the toughened epoxy resin composition are listed, and the beneficial effects of selecting the above ranges of component contents will be illustrated by specific experimental data.

[0090] Embodiment

[0091] It should be noted that, unless otherwise specified, the raw materials in the following embodiments can be obtained from the market. Among them, the curing agent is selected from dicyandiamide powder.

[0092] Embodiment 1: A method for preparing a toughened epoxy resin composition, comprising the following steps:

[0093] After 25 kg of bisphenol A type liquid epoxy resin, 25 kg of bisphenol F type liquid epoxy resin, 25 kg of bisphenol A type solid epoxy resin, 25 kg of phenolic epoxy resin, and 5 kg of polyether sulfone are placed in a reaction kettle, they are heated and dissolved, then 10 kg of curing agent and 1 kg of 2-methyl imidazole are added, stirred uniformly, and vacuum degassed to obtain a toughened epoxy resin composition.

[0094] In order to more clearly explain the technical solutions of the present application, embodiments 2-9 of the toughened epoxy resin composition are also listed, wherein the formulations of embodiments 2-9 are shown in Table 1.

[0095] Table 1 shows specific embodiments of the toughened epoxy resin composition in the present application. It should be noted that, in addition to the parameters listed in Table 1, the other parameters of embodiments 2-9 are basically the same as those of embodiment 1.

[0096] In Table 1, the ratio C1 is the weight ratio of the liquid epoxy resin and the solid epoxy resin;

[0097] The ratio C2 is the weight ratio of the bisphenol A type liquid epoxy resin, the bisphenol F type liquid epoxy resin and the thermoplastic toughening resin;

[0098] The ratio C3 is the weight ratio of the bisphenol A type solid epoxy resin and the phenolic epoxy resin;

[0099] The ratio C4 is the weight ratio of the bisphenol F type solid epoxy resin and the phenolic epoxy resin.

[0100] Table 1 Formulation table of Examples 1-9

[0101]

[0102] Comparative Example

[0103] Comparative Example 1: A method for preparing a toughened epoxy resin composition, comprising the following steps:

[0104] After placing 25 kg of bisphenol A type liquid epoxy resin, 25 kg of bisphenol F type liquid epoxy resin and 50 kg of bisphenol A type solid epoxy resin in a reaction kettle, the mixture was heated and dissolved, and then 10 kg of a curing agent and 1 kg of 2-methylimidazole were added. After stirring uniformly, vacuum degassing was performed to obtain a toughened epoxy resin composition.

[0105] Performance test

[0106] Resin samples and composite laminates were prepared according to the following method, and the performance of the resin samples and the composite laminates was tested, and the test results are recorded in Table 2.

[0107] The toughened epoxy resin compositions prepared in the examples and the comparative examples were made into resin samples, and the plane strain fracture toughness K Ic of the resin samples was tested. K Ic is used to describe the ability of a material to resist the unstable expansion of a crack in a plane strain state. The higher K Ic is, the stronger the material's ability to resist crack expansion, and the better the toughness of the material.

[0108] The toughened epoxy resin compositions prepared in the examples and the comparative examples were placed in a glue spreading machine to prepare a glue film at a temperature of 70°C; T700 grade 12K carbon fibers were selected, and the glue film was coated on the surface of the carbon fibers, and the impregnation temperature was controlled at 85°C to obtain a prepreg; the prepreg was cured at a temperature of 150°C for 30 min to prepare a composite laminate.

[0109] The compression after impact (CAI) and 0-degree bending strength of the composite laminate were tested. The CAI refers to the maximum compressive stress that the composite laminate can withstand when subjected to compression loading after being damaged by low-speed impact; the greater the CAI, the higher the residual compressive strength of the composite laminate after being damaged by impact, and the better the impact resistance of the composite laminate. The 0-degree bending strength refers to the maximum stress that the material can withstand when subjected to bending load in the 0-degree direction (i.e., the fiber direction), and can be used to measure the bending resistance of the material in the fiber direction; the greater the 0-degree bending strength, the better the bending performance and toughness of the composite laminate in the fiber direction.

[0110] Table 2 Performance test table of resin samples and laminates of Examples 1-9 and Comparative Example 1

[0111]

[0112] It can be seen from the data in Tables 1 and 2 that the toughened epoxy resin composition prepared by using the embodiments of the present application has high toughness, and the composite material prepared from the toughened epoxy resin composition has good impact resistance; it can be seen from Examples 1-9 that the amount and ratio of each component in the toughened epoxy resin composition have a significant effect on the performance of the material. Moreover, the amount and ratio of each component have a significant effect on the viscosity and processability of the toughened epoxy resin composition.

[0113] Figure 1 FIG. 1 is a viscosity-temperature curve of the toughened epoxy resin composition of Example 1, in which the abscissa is temperature (unit, ℃) and the ordinate is viscosity (unit, Pa·s); the viscosity-temperature curve can directly show the change of the viscosity of the material with temperature. According to the viscosity-temperature curve, the viscosity of the toughened epoxy resin composition of Example 1 at 124 ℃ is 0.7 Pa·s, which indicates that the overall viscosity and processability of the toughened epoxy resin composition can be improved by adjusting the formula, and the toughened epoxy resin composition is suitable for a medium-temperature curing process. Figure 1 It can be seen that the viscosity of the toughened epoxy resin composition of Example 1 at 124 ℃ is 0.7 Pa·s, which indicates that the overall viscosity and processability of the toughened epoxy resin composition can be improved by adjusting the formula, and the toughened epoxy resin composition is suitable for a medium-temperature curing process.

[0114] It should be noted that in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such a process, method, article, or equipment.

[0115] The above examples are only used to illustrate the technical solutions of the present application, rather than limit them. Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent ones, and these modifications or replacements 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 the present application.

Claims

1. A toughened epoxy resin composition, characterized in that The toughened epoxy resin composition comprises the following components in parts by weight: 100-120 parts by weight of epoxy resin mixture; 4-15 parts by weight of thermoplastic toughening resin; 10-20 parts by weight of a curing agent; The epoxy resin mixture includes liquid epoxy resin and solid epoxy resin in a preset weight ratio.

2. The toughened epoxy resin composition according to claim 1, characterized in that The preset weight ratio is 0.67-1.18:

1.

3. The toughened epoxy resin composition according to claim 1, characterized in that The liquid epoxy resin includes one or more of bisphenol A liquid epoxy resin and bisphenol F liquid epoxy resin; and / or The solid epoxy resin includes one or more of bisphenol A solid epoxy resin, bisphenol F solid epoxy resin, and novolac epoxy resin.

4. The toughened epoxy resin composition according to claim 3, characterized in that When the liquid epoxy resin comprises bisphenol A liquid epoxy resin and bisphenol F liquid epoxy resin, the weight ratio of the bisphenol A liquid epoxy resin, the bisphenol F liquid epoxy resin and the thermoplastic toughening resin is 2.50-5.00:1.67-5.00:

1.

5. The toughened epoxy resin composition according to claim 3, characterized in that When the solid epoxy resin comprises a bisphenol A solid epoxy resin and a novolac epoxy resin, the weight ratio of the bisphenol A solid epoxy resin to the novolac epoxy resin is 1.00-4.00:1; When the solid epoxy resin comprises bisphenol F epoxy resin and novolac epoxy resin, the weight ratio of the bisphenol F solid epoxy resin to the novolac epoxy resin is 1.07-2.24:

1.

6. The toughened epoxy resin composition according to claim 1, characterized in that The thermoplastic toughening resin includes one or more of polyphenol oxide resin, polyethersulfone resin, polyamide resin, polyphenylene ether resin, and polysulfone resin; and / or The curing agent includes dicyandiamide.

7. The toughened epoxy resin composition according to any one of claims 1 to 6, characterized in that The toughened epoxy resin composition further comprises 1-5 parts by weight of an accelerator.

8. The toughened epoxy resin composition according to claim 7, characterized in that The accelerator includes one or more of 2-methylimidazole, 3-phenyl-1,1-dimethylurea, and triphenylphosphine.

9. A prepreg, characterized in that The prepreg comprises the toughened epoxy resin composition according to any one of claims 1 to 8.

10. A composite material, characterized in that The composite material is formed by curing the prepreg according to claim 9, the curing temperature is 120-150° C., and the curing time is 30-60 minutes.

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