A high-toughness epoxy resin composition and a method for preparing the same

Abstract

The application provides a high-toughness epoxy resin composition and a preparation method thereof. The high-toughness epoxy resin composition comprises the following raw materials in mass parts: 100 parts of an epoxy resin, 10-20 parts of a first active filler, 10-20 parts of a first active diluent, 25-40 parts of a curing agent, 5-10 parts of a second active filler and 5-10 parts of a second active diluent. The first active filler is a first block polymer grafted first filler, the first block polymer comprises a first hard segment and a first soft segment, and the first block polymer comprises an epoxy group. The second active filler is a second block polymer grafted second filler, the second block polymer comprises a second hard segment and a second soft segment, and the second block polymer comprises an amino group. The high-toughness epoxy resin composition comprises the above raw materials in mass parts, and the raw materials are synergistic with each other, so that the epoxy resin composition can have high strength and good toughness.

Description

Technical Field

[0001] This application relates to the field of epoxy resin technology, specifically to a high-toughness epoxy resin composition and its preparation method. Background Technology

[0002] Epoxy resin materials are widely used in aerospace, automotive manufacturing, electronic packaging, and building structures due to their excellent mechanical properties, chemical resistance, heat resistance, and outstanding adhesion. However, traditional epoxy resin materials form a highly cross-linked three-dimensional network structure during the curing process. While this improves the material's thermal stability and chemical resistance, it inevitably leads to higher brittleness and insufficient impact toughness. This inherent brittleness limits its application in high-impact, dynamic-load, and extreme environments.

[0003] To address the problem of high brittleness in epoxy resin materials, scholars and engineers both domestically and internationally have explored various modification methods, including the introduction of flexible toughening agents such as rubber, thermoplastic polymers, nanoparticles, and block copolymers, in order to improve the toughness and impact resistance of epoxy resin materials while maintaining their high strength.

[0004] Toughening agents are prone to phase separation or aggregation in epoxy resin matrices, thus affecting the overall performance of epoxy resin materials. Furthermore, some flexible toughening agents have poor compatibility with epoxy resins, which may lead to microscopic defects during curing, reducing the strength of the final product. Additionally, controlling the curing reaction and crosslinking density is difficult; to improve toughness, it is often necessary to reduce the crosslinking density, but this may result in a decrease in the strength of the epoxy resin material.

[0005] Patent CN119505484A discloses an epoxy resin composition and its preparation method, as well as an epoxy resin prepreg and its preparation method. The method includes the following steps: mixing epoxy resin, 2,4-diphenylmethane diisocyanate, and 4,4-diphenylmethane diisocyanate and synthesizing them under the action of a catalyst to obtain a transparent toughening agent; mixing the mixed epoxy resin and the transparent toughening agent to obtain a first mixture; adding an antifoaming agent, an ultraviolet absorber, an antioxidant, a light stabilizer, and a fluorescent agent to obtain a second mixture; cooling the second mixture to 60-70°C, adding a curing agent and an accelerator, and mixing under vacuum for 0.3-0.4 hours to obtain the epoxy resin composition. The epoxy resin composition provided by this invention possesses heat resistance, high transparency, yellowing resistance, and high toughness.

[0006] Therefore, there is a need to provide a high-toughness epoxy resin composition with high strength and good flexibility. Summary of the Invention

[0007] This application provides a high-toughness epoxy resin composition and its preparation method, which can achieve both high strength and good toughness.

[0008] In a first aspect, this application provides a high-toughness epoxy resin composition comprising the following raw materials in parts by weight: 100 parts epoxy resin, 10-20 parts first active filler, 10-20 parts first active diluent, 25-40 parts curing agent, 5-10 parts second active filler, and 5-10 parts second active diluent; wherein the first active filler is a first block polymer grafted with the first filler, the first block polymer comprising a first hard segment and a first soft segment, and the first block polymer comprising epoxy groups; the second active filler is a second block polymer grafted with the second filler, the second block polymer comprising a second hard segment and a second soft segment, and the second block polymer comprising amino groups.

[0009] According to this application, the high-toughness epoxy resin composition comprises the above-mentioned parts by weight of raw materials, each of which has good reactivity. After mixing, the raw materials can form a network structure with high crosslinking density. At the same time, the first and second active fillers are both modified by block polymer activation, and have good compatibility with the epoxy resin system. The two aspects work together to give the obtained crosslinked product high strength. Meanwhile, the flexible segments on the first and second active fillers, together with the first and second active diluents, can give the cured epoxy resin composition good toughness. Thus, the epoxy resin composition can achieve both high strength and good toughness.

[0010] Specifically, the high-toughness epoxy resin composition is a product of crosslinking epoxy resin under the action of a curing agent. Its properties are mainly determined by the types and proportions of each raw material. The first and second active fillers are grafted with block polymers containing active groups, which effectively improves the compatibility of the fillers in the epoxy resin system and promotes uniform dispersion of the fillers within the system. Simultaneously, the active groups can participate in the crosslinking reaction, achieving chemical bonding with each component during curing and increasing the crosslinking density of the crosslinking product. Furthermore, the rigid fillers and hard segments in the block polymers are grafted into the epoxy resin crosslinking network, effectively improving the strength of the cured composition. On the other hand, the use of the first and second active diluents can promote the dispersion of the first and second active fillers in the epoxy resin and curing agent, respectively, making it easier for the components to mix and react fully, resulting in a more uniform crosslinking density in the cured epoxy resin composition. At the same time, the active diluents can also participate in the curing crosslinking reaction. The flexible segments in the active diluents, in conjunction with the flexible segments on the first and second active fillers, provide elasticity and energy dispersion in the cured epoxy resin composition, which helps alleviate stress concentration and thus improves the toughness of the cured epoxy resin composition.

[0011] In addition, it is understandable that both the first and second reactive diluents participate in the curing and crosslinking reaction. Therefore, this high-toughness epoxy resin composition has no solvent evaporation, resulting in less environmental pollution and conforming to environmentally friendly chemistry.

[0012] In some embodiments, the first hard segment includes an epoxy group; the second soft segment includes an amino group.

[0013] In some of the above embodiments, the active epoxy groups in the first active filler are grafted onto the first hard chain segment, and the active amino groups in the second active filler are grafted onto the second soft chain segment. The resulting cured epoxy resin composition exhibits better strength and toughness. This may be because epoxy groups mainly react with the curing agent and the second active diluent in the system, and their chain segments are highly flexible. If epoxy groups are grafted onto the soft chain segment, it will affect the strength of the cured epoxy resin composition. Meanwhile, amino groups serve as crosslinking sites for epoxy resin. Grafting amino groups onto the soft chain segment can balance the impact of increased crosslinking density on toughness. Thus, by grafting epoxy groups onto the first hard chain segment and amino groups onto the second soft chain segment, the distribution of flexible and hard segments in the crosslinking network becomes more reasonable, and the flexible segments better compensate for the impact of crosslinking density on toughness, thereby better balancing the strength and toughness of the cured epoxy resin composition.

[0014] In some embodiments, the method for preparing the first active filler includes the following steps:

[0015] S1: The first filler was modified by silanization with propyl 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) ester, and free radical reactive groups were grafted onto the surface of the first filler to obtain the modified first filler;

[0016] S2: The modified first filler is subjected to free radical polymerization with methyl methacrylate and glycidyl methacrylate under catalysis in an organic solvent, and hard segments are grafted onto the surface of the first filler to obtain the first reaction solution;

[0017] S3: Butyl acrylate is added to the first reaction solution, and free radical polymerization occurs under catalytic conditions in an organic solvent. Soft segments are then grafted onto the hard segments to obtain the first active filler.

[0018] In some of the above embodiments, a method for preparing the first active filler is specifically defined. The first active filler obtained by using this method results in a cured epoxy resin composition with better strength and toughness. Specifically, the first filler is first functionalized using propyl 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) ester, grafting free radical reactive groups onto the surface of the first filler to provide active sites for subsequent free radical polymerization of monomers. Then, methyl methacrylate and glycidyl methacrylate are used as functional monomers to undergo free radical copolymerization at the active sites on the surface of the first filler. The copolymer of methyl methacrylate and glycidyl methacrylate serves as the rigid segment on the surface of the first active filler. Polymethyl methacrylate has a high glass transition temperature and strong rigidity, while glycidyl methacrylate can provide active epoxy groups. After the rigid segment grafting is completed, butyl acrylate is directly added to the reaction system for free radical polymerization. Polybutyl acrylate is then grafted onto the rigid segment as a flexible segment. Because polybutyl acrylate has long side chains, its molecular chains are more mobile and it has a lower glass transition temperature, thus exhibiting good flexibility.

[0019] The resulting first active filler has hard and soft segments grafted sequentially onto its surface. The inventors discovered that grafting the hard segments closer to the filler can further improve the strength and toughness of the cured epoxy resin composition. This is likely because the high strength and structural support of the hard segments, combined with the grafted epoxy groups, can significantly improve the interfacial adhesion between the filler and the components in the system. This allows the filler to fully exert its reinforcing effect and improve the strength of the cured epoxy resin composition. At the same time, the soft segments grafted on the outside can further improve the dispersibility of the first active filler in the system, making it easier to disperse the stress through the movement of external molecular chains, thereby improving the toughness of the cured epoxy resin composition. Thus, the first active filler obtained by the above method can further improve the strength and toughness of the cured epoxy resin composition.

[0020] In some embodiments, the method for preparing the first active filler includes the following steps:

[0021] S1: 20 parts of the first filler, 5-15 parts of propyl 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) ester, and 0.1-2 parts of triethylamine are dispersed in 500-1000 parts of toluene and refluxed at 90-110℃ for 18-24 h to obtain the modified first filler;

[0022] S2: 20 parts of modified first filler, 15-20 parts of methyl methacrylate, and 1-3 parts of glycidyl methacrylate are dispersed in 150-300 parts by mass of N,N-dimethylformamide, and 0.1-1 parts of cuprous bromide and 0.1-1 parts of pentamethyldiethylenetriamine are used as catalysts. The mixture is reacted at 80-90℃ under a protective atmosphere for 3-5 hours to obtain the first reaction solution.

[0023] S3: Add 15-20 parts of butyl acrylate to the first reaction solution and react at 75-85℃ under a protective atmosphere for 3-5 hours to obtain the first active filler.

[0024] In some of the above embodiments, the reaction conditions of each step in the preparation method of the first active filler are specifically defined. Under these conditions, the first active filler can better balance the strength and toughness of the cured epoxy resin composition. It can be understood that by controlling the ratio between the filler and each functional monomer, the length of the soft chain segment and the hard chain segment, as well as the number of active groups, can be controlled. Under the above conditions, a first active filler with appropriate soft chain segment and hard chain segment lengths can be grafted onto the surface of the first filler, and it can have better reactivity, so that the cured epoxy resin composition has better strength and toughness.

[0025] In some embodiments, the method for preparing the second active filler includes the following steps:

[0026] M1: The second filler was modified by silanization with propyl 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) and free radical reactive groups were grafted onto the surface of the second filler to obtain the modified second filler.

[0027] M2: The modified second filler and methyl methacrylate undergo a free radical polymerization reaction under catalysis in an organic solvent, and hard segments are grafted onto the surface of the second filler to obtain the second reaction solution;

[0028] M3: Butyl acrylate and 4-hydroxybutyl acrylate are added to the second reaction solution, and free radical polymerization reaction is carried out under catalytic conditions and in an organic solvent. Soft segments are grafted onto the hard segments to obtain hydroxyl-containing block polymer grafted filler.

[0029] M4: The hydroxyl-containing block polymer grafted filler is modified with an aminosilane coupling agent, so that the hydroxyl groups on the soft segments of the block polymer grafted filler react with the aminosilane coupling agent to obtain the second active filler.

[0030] In some of the above embodiments, a specific method for preparing the second active filler is defined. The second active filler obtained using this method results in a cured epoxy resin composition with better strength and toughness. Specifically, 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester is first used to graft sites available for free radical polymerization onto the surface of the second filler. Then, methyl methacrylate is used as a functional monomer to polymerize polymethyl methacrylate as a hard segment. Subsequently, butyl acrylate and 4-hydroxybutyl acrylate are added to the system as functional monomers to polymerize a copolymer of butyl acrylate and 4-hydroxybutyl acrylate as a soft segment. Finally, an aminosilane coupling agent is used to react with the hydroxyl groups on the soft segment, thereby grafting active amino groups onto the soft segment to obtain the second active filler.

[0031] The resulting second active filler surface is sequentially grafted with hard and soft segments. The soft segments containing amino groups grafted on the side away from the second filler surface can further improve the strength and toughness of the cured epoxy resin composition. This may be because the amino groups, as sites for crosslinking of epoxy resin, can reduce the influence of steric hindrance on the crosslinking of epoxy resin when grafted on the side away from the second filler surface, thereby increasing the crosslinking density of the crosslinking product. At the same time, the flexible segments on the outer side can more easily disperse the stress on the cured epoxy resin composition by moving, thereby further improving the strength and toughness of the cured epoxy resin composition.

[0032] In some embodiments, the method for preparing the second active filler includes the following steps:

[0033] M1: 20 parts of the second filler, 5-15 parts of propyl 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) ester, and 0.1-2 parts of triethylamine are dispersed in 500-1000 parts of toluene and refluxed at 90-110℃ for 18-24 h to obtain the modified second filler;

[0034] M2: 20 parts of modified second filler and 15-20 parts of methyl methacrylate are dispersed in 150-300 parts by mass of N,N-dimethylformamide, and 0.1-1 parts of cuprous bromide and 0.1-1 parts of pentamethyldiethylenetriamine are used as catalysts. The mixture is reacted at 80-90℃ under a protective atmosphere for 3-5 hours to obtain the second reaction solution.

[0035] M3: Add 15-20 parts of butyl acrylate and 1-3 parts of 4-hydroxybutyl acrylate to the second reaction solution, and react at 75-85°C under a protective atmosphere for 3-5 hours to obtain hydroxyl-containing block polymer grafted filler.

[0036] M4: Disperse 20 parts of hydroxyl-containing block polymer grafted filler, 5-10 parts of aminosilane coupling agent, and 0.1-1 parts of triethylamine in 300-600 parts of toluene, and reflux at 80-100℃ for 3-8 hours to obtain the second active filler.

[0037] In some of the above embodiments, the reaction conditions of each step in the preparation method of the second active filler are specifically defined. Under these conditions, the second active filler can better balance the strength and toughness of the cured epoxy resin composition. Under the above conditions, a second active filler with suitable soft and hard chain segment lengths can be grafted onto the surface of the second filler, and it has good reactivity, so that the cured epoxy resin composition has better strength and toughness.

[0038] In some implementations, the protective gas is nitrogen or argon.

[0039] In some embodiments, the aminosilane coupling agent includes N-aminoethyl-γ-aminopropyltrimethoxysilane.

[0040] In some of the above embodiments, the inventors found that the second active filler obtained by using different aminosilane coupling agents has a certain influence on the strength and toughness of the cured epoxy resin composition. When N-aminoethyl-γ-aminopropyltrimethoxysilane is used as the aminosilane coupling agent, the cured epoxy resin composition can better balance strength and toughness. The possible reason is that after N-aminoethyl-γ-aminopropyltrimethoxysilane reacts with hydroxyl groups, the active group on the segment grafted onto the second flexible segment includes not only a primary amine group but also a secondary amine group. The secondary amine group can also participate in the curing reaction of the epoxy resin. Compared with 3-aminopropyltrimethoxysilane as the aminosilane coupling agent, this method is more effective. It can provide more reaction sites, which can appropriately increase the crosslinking density, thereby further improving the strength of the cured epoxy resin composition. Moreover, the secondary amine group has only one active hydrogen and reacts with only one epoxy group. Compared with the primary amine group, its reaction product has a lower degree of crosslinking and will not significantly deteriorate the toughness of the cured epoxy resin composition. In addition, compared with diethylenetriaminepropyltrimethoxysilane, this silane coupling agent contains one primary amine group and two secondary amine groups, which further increases the reaction sites and the crosslinking density may deteriorate the toughness of the cured epoxy resin composition. Therefore, the use of N-aminoethyl-γ-aminopropyltrimethoxysilane can better balance the strength and toughness of the cured epoxy resin composition.

[0041] In some embodiments, the first active filler and the second active filler obtained by the above two methods are used simultaneously. In this case, due to steric hindrance, the epoxy groups on the hard segments of the first active filler are not easy to react with the amino groups on the soft segments of the second active filler. This allows the active fillers to react with the epoxy resin and the curing agent respectively, making the fillers more evenly distributed in the system and giving the cured epoxy resin composition better strength and toughness.

[0042] In some embodiments, the first reactive diluent comprises an epoxy-containing glycidyl ether, and the second reactive diluent comprises an amino-containing polyetheramine.

[0043] In some of the above embodiments, the first reactive diluent includes reactive epoxy groups, and the second reactive diluent includes amino groups. Both can participate in the curing and crosslinking reaction, increasing the crosslinking density. Simultaneously, their residual chain segments exhibit good flexibility. Combined with the flexible chain segments of the first and second reactive fillers, this results in the cured epoxy resin composition possessing better strength and toughness. As an example, in one embodiment of this application, the first reactive diluent is ethylene glycol diglycidyl ether, and the second reactive diluent is polyetheramine 400.

[0044] In some embodiments, the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin. As an example, in one embodiment of this application, the epoxy resin is epoxy resin E44.

[0045] In some embodiments, the curing agent includes at least one of polyamide 300, polyamide 650, and polyamide 651. As an example, in one embodiment of this application, the curing agent is polyamide 300.

[0046] In some embodiments, the first filler and the second filler each independently comprise at least one of nano-calcium carbonate, nano-silica, and titanium dioxide. As an example, in one embodiment of this application, the first filler and the second filler are nano-calcium carbonate with a particle size of 50-100 nm.

[0047] Secondly, this application provides a method for preparing a high-toughness epoxy resin composition, comprising:

[0048] A raw material for a high-toughness epoxy resin composition according to any embodiment of the first aspect is provided; an epoxy resin, a first active filler and a first active diluent are mixed to obtain a first component; a curing agent, a second active filler and a second active diluent are mixed to obtain a second component; and the first component and the second component are mixed and cured to obtain a high-toughness epoxy resin composition.

[0049] According to this application, the method includes the raw materials of the high-toughness epoxy resin composition in any embodiment of the first aspect, and therefore the high-toughness epoxy resin composition obtained by the method has the beneficial effects of the first aspect.

[0050] It is understandable that the first component is obtained by mixing an epoxy resin containing active epoxy groups, a first active filler, and a first active diluent, and the second component is obtained by mixing a curing agent containing active amino groups, a second active filler, and a second active diluent. When using, the two components are mixed and cured to obtain a high-toughness epoxy resin composition.

[0051] Compared to existing technologies, the beneficial effects of this application are at least as follows:

[0052] The high-toughness epoxy resin composition provided in this application optimizes the raw material components, and the cured product can achieve both high strength and good toughness. At the same time, all raw materials can participate in the cross-linking curing reaction, and the solvent-free formulation helps to reduce environmental pollution. Due to its excellent properties, this high-toughness epoxy resin composition can be used in adhesives, coatings and other fields. Detailed Implementation

[0053] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0054] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0056] In this specification, unless otherwise specified, "parts" refers to "parts by weight".

[0057] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0058] The CAS numbers of some of the reagents used in the examples are as follows:

[0059] 2-Bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester, CAS No. 314021-97-1;

[0060] Pentamethyldiethylenetriamine, CAS number 3030-47-5;

[0061] 3-Aminopropyltriethoxysilane, CAS number 13822-56-5;

[0062] N-aminoethyl-γ-aminopropyltrimethoxysilane, CAS number 1760-24-3;

[0063] Diethylenetriaminepropyltrimethoxysilane, CAS number 35141-30-1.

[0064] Preparation Example 1

[0065] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0066] 20 parts of modified nano-calcium carbonate, 15 parts of methyl methacrylate and 2 parts of glycidyl methacrylate were dissolved and dispersed in 200 parts of N,N-dimethylformamide. Oxygen was removed from the system, and 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added. The mixture was heated at 90°C for 4 hours under a nitrogen atmosphere to obtain the first reaction solution.

[0067] Add 15 parts of butyl acrylate to the first reaction solution, heat at 85°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain the first active filler A (denoted as SY(O)-R, where S represents the filler, Y represents the hard segment, R represents the soft segment, and (O) represents the epoxy group grafted onto the segment).

[0068] Preparation Example 2

[0069] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0070] 20 parts of modified nano-calcium carbonate and 15 parts of butyl acrylate were dispersed in 200 parts of N,N-dimethylformamide to remove oxygen from the system. 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added, and the mixture was heated at 85°C for 4 hours under a nitrogen atmosphere to obtain the first reaction solution.

[0071] Add 15 parts of methyl methacrylate and 2 parts of glycidyl methacrylate to the first reaction solution, heat at 90°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain the first active filler B (denoted as SRY(O)).

[0072] Preparation Example 3

[0073] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0074] 20 parts of modified nano-calcium carbonate and 15 parts of methyl methacrylate were dissolved and dispersed in 200 parts of N,N-dimethylformamide to remove oxygen from the system. 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added, and the mixture was heated at 90°C for 4 hours under a nitrogen atmosphere to obtain the first reaction solution.

[0075] Then, 15 parts of butyl acrylate and 2 parts of 4-hydroxybutyl acrylate glycidyl ether were added to the first reaction solution. The mixture was heated at 85°C for 4 hours under a nitrogen atmosphere. After centrifugation, the mixture was washed with N,N-dimethylformamide and dried to obtain the first active filler C (denoted as SYR(O)).

[0076] Preparation Example 4

[0077] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0078] 20 parts of modified nano-calcium carbonate and 15 parts of methyl methacrylate were dissolved and dispersed in 200 parts of N,N-dimethylformamide to remove oxygen from the system. 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added, and the mixture was heated at 90°C for 4 hours under a nitrogen atmosphere to obtain the second reaction solution.

[0079] Add 15 parts of butyl acrylate and 2 parts of 4-hydroxybutyl acrylate to the second reaction solution, heat at 85°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain hydroxyl-containing block polymer grafted calcium carbonate.

[0080] 20 parts of hydroxyl-containing block polymer grafted calcium carbonate, 8 parts of N-aminoethyl-γ-aminopropyltrimethoxysilane, and 0.1 parts of triethylamine were dispersed in 400 parts of toluene. The mixture was heated under reflux at 85°C for 6 hours, centrifuged, washed with water, and dried to obtain the second active filler A (denoted as SYR(N), where (N) represents the amino group grafted onto the chain segment).

[0081] Preparation Example 5

[0082] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0083] 20 parts of modified nano-calcium carbonate, 15 parts of butyl acrylate and 2 parts of 4-hydroxybutyl acrylate were dispersed in 200 parts of N,N-dimethylformamide. Oxygen was removed from the system, and 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added. The mixture was heated at 85°C for 4 hours under a nitrogen atmosphere to obtain the second reaction solution.

[0084] Add 15 parts of methyl methacrylate to the second reaction solution, heat at 90°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain hydroxyl-containing block polymer grafted calcium carbonate.

[0085] 20 parts of hydroxyl-containing block polymer grafted calcium carbonate, 8 parts of N-aminoethyl-γ-aminopropyltrimethoxysilane, and 0.1 parts of triethylamine were dispersed in 400 parts of toluene and heated under reflux at 85°C for 6 hours. After centrifugation, washing with water, and drying, the second active filler B (denoted as SR(N)-Y) was obtained.

[0086] Preparation Example 6

[0087] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0088] 20 parts of modified nano-calcium carbonate, 15 parts of methyl methacrylate and 2 parts of hydroxypropyl methacrylate were dissolved and dispersed in 200 parts of N,N-dimethylformamide. After removing oxygen from the system, 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added. The mixture was heated at 90°C for 4 hours under a nitrogen atmosphere to obtain the second reaction solution.

[0089] Add 15 parts of butyl acrylate to the second reaction solution, heat at 85°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain hydroxyl-containing block polymer grafted calcium carbonate.

[0090] 20 parts of hydroxyl-containing block polymer grafted calcium carbonate, 8 parts of N-aminoethyl-γ-aminopropyltrimethoxysilane, and 0.1 parts of triethylamine were dispersed in 400 parts of toluene and heated under reflux at 85°C for 6 hours. After centrifugation, washing with water, and drying, the second active filler C (denoted as SY(N)-R) was obtained.

[0091] Preparation Example 7

[0092] The preparation method is largely the same as in Example 4, except that 3-aminopropyltriethoxysilane is used instead of N-aminoethyl-γ-aminopropyltrimethoxysilane to obtain the second active filler A1.

[0093] Preparation Example 8

[0094] The preparation method is largely the same as in Example 4, except that diethylenetriaminepropyltrimethoxysilane is used instead of N-aminoethyl-γ-aminopropyltrimethoxysilane to obtain the second active filler A2.

[0095] Preparation Example 9

[0096] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0097] 20 parts of modified nano-calcium carbonate and 15 parts of methyl methacrylate were dissolved and dispersed in 200 parts of N,N-dimethylformamide to remove oxygen from the system. 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added, and the mixture was heated at 90°C for 4 hours under a nitrogen atmosphere to obtain the first reaction solution.

[0098] Add 15 parts of butyl acrylate to the first reaction solution, heat at 85°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain filler A (denoted as SYR).

[0099] Preparation Example 10

[0100] 20 parts of nano-calcium carbonate were ultrasonically dispersed in 600 parts of toluene, 10 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl)propyl ester and 0.2 parts of triethylamine were added, and the mixture was heated under reflux at 105°C for 24 h. After centrifugation, the mixture was washed with ethanol and dried to obtain modified nano-calcium carbonate.

[0101] 20 parts of modified nano-calcium carbonate and 15 parts of butyl acrylate were dispersed in 200 parts of N,N-dimethylformamide to remove oxygen from the system. 0.5 parts of cuprous bromide and 0.5 parts of pentamethyldiethylenetriamine were added, and the mixture was heated at 85°C for 4 hours under a nitrogen atmosphere to obtain the first reaction solution.

[0102] Add 15 parts of methyl methacrylate to the first reaction solution, heat at 90°C for 4 hours under a nitrogen atmosphere, centrifuge, wash with N,N-dimethylformamide, and dry to obtain filler B (denoted as SRY).

[0103] Example 1

[0104] Preparation of high-toughness epoxy resin composition:

[0105] The first component is obtained by mixing 100 parts of epoxy resin E44, 15 parts of first active filler A, and 12 parts of ethylene glycol diglycidyl ether.

[0106] The second component was obtained by mixing 35 parts of polyamide 300, 8 parts of second active filler A, and 8 parts of polyetheramine 400.

[0107] Example 2

[0108] It is largely the same as Example 1, except that the second active filler B is used instead of the second active filler A.

[0109] Example 3

[0110] It is largely the same as Example 1, except that the second active filler C is used instead of the second active filler A.

[0111] Example 4

[0112] It is largely the same as Example 1, except that the second active filler A1 is used instead of the second active filler A.

[0113] Example 5

[0114] It is largely the same as Example 1, except that the second active filler A2 is used instead of the second active filler A.

[0115] Example 6

[0116] It is largely the same as Example 1, except that the first active filler B is used instead of the first active filler A.

[0117] Example 7

[0118] It is largely the same as Example 1, except that the first active filler C is used instead of the first active filler A.

[0119] Comparative Example 1

[0120] Similar to Example 1, except that filler A is used instead of the first active filler A and the second active filler B.

[0121] Comparative Example 2

[0122] Similar to Example 1, except that filler B is used instead of the first active filler A and the second active filler B.

[0123] Test section

[0124] After the epoxy resin compositions of each embodiment and comparative example were mixed and cured, their tensile strength and elongation at break were tested according to GB / T 2567-2008. The results are shown in Table 1.

[0125] Table 1

[0126]

[0127] As shown in Table 1, the tensile strength of the cured epoxy resin compositions obtained in each embodiment is significantly higher than that of Comparative Example 1. The elongation at break of each embodiment is higher than that of Comparative Example 2. Except for Examples 2 and 6, the elongation at break of each embodiment is higher than that of Comparative Example 1, indicating that the cured epoxy resin compositions obtained in each embodiment can better balance strength and toughness. The fillers used in Comparative Examples 1 and 2 are not grafted with active groups and do not have reactive activity with the components in the epoxy resin composition. Therefore, their crosslinking density is low, and their strength is significantly lower than that of each embodiment. At the same time, although the block polymer grafted on the filler surface can improve the dispersibility of the filler in the system to a certain extent, it has limited improvement on compatibility compared with reactive block polymers. Although the flexible segments in the block polymer can disperse stress to a certain extent, their poor compatibility has limited improvement on toughness. By comparison, it can be seen that the flexible segments grafted on the side away from the filler are more effective in improving the compatibility of the filler and dispersing tensile stress.

[0128] Comparative Examples 1-3, 6, and 7 show that the positions of the hard and flexible segments, and the grafting sites of the active groups in the first and second active fillers, all have a certain influence on the strength and toughness of the cured epoxy resin composition. The cured epoxy resin composition obtained in Example 1 exhibits better strength and toughness. Results from Examples 2 and 6 indicate that grafting the flexible segments onto the outside of the filler has a better effect on improving the performance of the epoxy resin composition. According to Examples 1, 3, and 7, grafting epoxy groups onto the hard segments and amino groups onto the flexible segments allows the epoxy resin composition to better balance strength and toughness.

[0129] By comparing Examples 1, 4, and 5, it can be seen that the type of aminosilane coupling agent used in the preparation of the second active filler has a certain influence on the strength and toughness of the cured epoxy resin composition. The second active filler obtained by using N-aminoethyl-γ-aminopropyltrimethoxysilane can better balance the strength and toughness of the cured epoxy resin composition.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A high toughness epoxy resin composition, characterized by comprising: a) an epoxy resin; b) a curing agent; c) a toughener; d) a curing catalyst; and e) a curing accelerator. The preparation method of the first active filler comprises the following steps: S1: the first filler is modified by silanization using 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) propyl ester to graft a free radical reaction active group on the surface of the first filler, and a modified first filler is obtained; S2: the modified first filler is subjected to a free radical polymerization reaction with methyl methacrylate and glycidyl methacrylate under catalytic conditions in an organic solvent to graft a hard segment on the surface of the first filler, and a first reaction liquid is obtained; S3: butyl acrylate is added to the first reaction liquid, and a free radical polymerization reaction is carried out under catalytic conditions in an organic solvent to continue to graft a soft segment on the hard segment, and the first active filler is obtained. The preparation method of the second active filler comprises the following steps: M1: the second filler is modified by silanization using 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) propyl ester to graft a free radical reaction active group on the surface of the second filler, and a modified second filler is obtained; M2: the modified second filler is subjected to a free radical polymerization reaction with methyl methacrylate under catalytic conditions in an organic solvent to graft a hard segment on the surface of the second filler, and a second reaction liquid is obtained; M3: butyl acrylate and 4-hydroxybutyl acrylate are added to the second reaction liquid, and a free radical polymerization reaction is carried out under catalytic conditions in an organic solvent to continue to graft a soft segment on the hard segment, and a hydroxyl-containing block polymer grafted filler is obtained; M4: the hydroxyl-containing block polymer grafted filler is modified using an amino silane coupling agent to make the hydroxyl groups on the soft segment of the block polymer grafted filler react with the amino silane coupling agent, and the second active filler is obtained. The first active diluent comprises an epoxy-containing glycidyl ether, and the second active diluent comprises an amino-containing polyether amine. The first filler and the second filler each independently comprise at least one of nano calcium carbonate, nano silicon dioxide and titanium white. The preparation method of the first active filler comprises the following steps: S1: 20 parts of the first filler, 5-15 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) propyl ester and 0.1-2 parts of triethylamine are dispersed in 500-1000 parts of toluene, and reflux reaction is carried out at 90-110°C for 18-24h to obtain a modified first filler; 2. The high toughness epoxy resin composition according to claim 1, characterized in that, S2: 20 parts of the modified first filler, 15-20 parts of methyl methacrylate and 1-3 parts of glycidyl methacrylate are dispersed in 150-300 parts of N,N-dimethylformamide, 0.1-1 part of cuprous bromide and 0.1-1 part of pentamethyldiethylenetriamine are used as catalysts, and reaction is carried out at 80-90°C under a protective atmosphere for 3-5h to obtain a first reaction liquid; S3: 15-20 parts of butyl acrylate are added to the first reaction liquid, and reaction is carried out at 75-85°C under a protective atmosphere for 3-5h to obtain the first active filler. ​ ​ 3. The high toughness epoxy resin composition according to claim 1, wherein The preparation method of the second active filler comprises the following steps: M1: dispersing 20 parts of the second filler, 5-15 parts of 2-bromo-2-methylpropionic acid (3-trimethoxysilyl) propyl ester, and 0.1-2 parts of triethylamine in 500-1000 parts of toluene, and refluxing at 90-110°C for 18-24 hours to obtain a modified second filler; M2: dispersing 20 parts of the modified second filler and 15-20 parts of methyl methacrylate in 150-300 parts of N,N-dimethylformamide, using 0.1-1 part of cuprous bromide and 0.1-1 part of pentamethyldiethylenetriamine as a catalyst, and reacting at 80-90°C in a protective atmosphere for 3-5 hours to obtain a second reaction liquid; M3: adding 15-20 parts of butyl acrylate and 1-3 parts of 4-hydroxybutyl acrylate to the second reaction liquid, and reacting at 75-85°C in a protective atmosphere for 3-5 hours to obtain a hydroxyl-containing block polymer grafted filler; M4: dispersing 20 parts of the hydroxyl-containing block polymer grafted filler, 5-10 parts of an aminosilane coupling agent, and 0.1-1 part of triethylamine in 300-600 parts of toluene, and refluxing at 80-100°C for 3-8 hours to obtain a second active filler.

4. The high toughness epoxy resin composition according to claim 3, wherein The aminosilane coupling agent comprises N-aminoethyl-γ-aminopropyl trimethoxysilane.

5. The high toughness epoxy resin composition according to claim 1, wherein The high-toughness epoxy resin composition satisfies at least one of the following conditions: 1) the epoxy resin comprises at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; 2) the curing agent comprises at least one of polyamide 300, polyamide 650, and polyamide 651.

6. A method of preparing a high toughness epoxy resin composition, characterized by, The method comprises: providing raw materials of the high-toughness epoxy resin composition according to any one of claims 1-5; mixing the epoxy resin, the first active filler, and the first active diluent to obtain a first component; mixing the curing agent, the second active filler, and the second active diluent to obtain a second component; mixing the first component and the second component to obtain the high-toughness epoxy resin composition.

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