Organic silicon toughened epoxy resin and preparation method thereof
By introducing thermoplastic polyetherimide and organosilicon into epoxy resin to form a ternary blend system, the contradiction between the toughness and heat resistance of epoxy resin is resolved, and a comprehensive performance improvement of high strength, high toughness and high heat resistance is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-03-20
AI Technical Summary
Existing technologies struggle to improve the toughness of epoxy resins while maintaining their high rigidity and heat resistance, and traditional rubber elastomer toughening methods can lead to a decrease in material modulus and heat resistance.
By introducing thermoplastic polyetherimide (PEI) and reactive organosilicon (such as terminal epoxy or amino silicone oil) to form a ternary blend system, the high heat resistance of PEI and the flexibility of organosilicon are utilized to induce phase separation to form a micro-phase structure, thereby enhancing the toughness and impact resistance of the material. Chemical bonding is achieved through a curing reaction with an acid anhydride curing agent.
It significantly improves the tensile strength, elongation at break, and shear strength of epoxy resin, forming a balance of high strength, high toughness, and high heat resistance, and possesses good hydrophobicity and dielectric properties.
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Figure CN121699338A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to an organosilicon toughened epoxy resin and its preparation method. Background Technology
[0002] Epoxy resins are widely used in high-end fields due to their excellent mechanical properties, adhesion, and chemical stability. However, their high crosslinking density and brittleness after curing limit their application in impact-resistant structural components. Traditional toughening methods using rubber elastomers can improve toughness, but often at the cost of significantly sacrificing the material's rigidity, strength, and heat resistance, making it difficult to meet the stringent requirements of high-performance composite materials for comprehensive properties. Polyetherimide (PEI), as a high-performance thermoplastic polymer, possesses high heat resistance, high modulus, and good mechanical properties. Introducing it into epoxy resin systems can induce controllable phase separation to form an "island" structure, efficiently absorbing impact energy through mechanisms such as plastic deformation and crack anchoring, significantly improving the fracture toughness and microcrack resistance of epoxy resins. Simultaneously, the high performance of the PEI phase itself can compensate for or even synergistically enhance the modulus and heat resistance of the matrix, providing an effective path to achieve a balance between high strength, high toughness, and high heat resistance. The current core challenge of this technology lies in precisely controlling the compatibility, phase morphology, and interfacial strength of the two phases to stably achieve the optimal toughening effect.
[0003] The inherent brittleness and poor crack resistance of epoxy resins are major obstacles to their structural applications. Conventional flexible toughening agents often introduce new problems such as decreased modulus, heat resistance, and moisture resistance when improving toughness. Organosilicon materials, with their extremely low glass transition temperature, exceptional flexibility, excellent hydrophobicity, and thermal stability, have become ideal toughening choices. By introducing reactive organosilicon (such as terminal epoxy or amino silicone oil), it can be partially chemically bonded to the epoxy matrix, inducing the formation of a soft phase structure with microscopic phase separation. These dispersed organosilicon particles can act as stress concentration points, terminating crack propagation and dissipating energy through mechanisms such as inducing crazes and shear bands, thereby significantly improving the fracture toughness and impact resistance of the material. In addition, the introduction of organosilicon components can also endow the system with excellent hydrophobicity, aging resistance, and dielectric properties, achieving multifunctional integrated modification. Currently, the bottleneck in the development of this technology lies in overcoming the significant compatibility differences between organosilicon and epoxy resin, and precisely controlling the microphase structure to solve the problem of balancing toughening efficiency and macroscopic performance. Summary of the Invention
[0004] In order to overcome at least one technical problem existing in the prior art, the present invention provides an organosilicon toughened epoxy resin and a method for preparing the same.
[0005] The technical solution of the present invention is as follows:
[0006] This invention first discloses a method for preparing organosilicon toughened epoxy resin, which includes the following steps: dissolving thermoplastic polyetherimide (PEI) in epoxy resin (EP), then adding epoxy-terminated polysiloxane (SiO), and stirring thoroughly to form an EP / PEI / SiO ternary blend system; then adding an acid anhydride curing agent, mixing evenly, and carrying out a curing reaction under high temperature conditions, and obtaining organosilicon toughened epoxy resin after the reaction is completed.
[0007] Preferably, the epoxy resin is a bisphenol A type epoxy resin.
[0008] Preferably, the epoxy equivalent of the bisphenol A type epoxy resin is 182-192 g / mol.
[0009] Preferably, the thermoplastic polyetherimide (PEI) is formed by the condensation polymerization of bisphenol A dianhydride and aromatic diamine at high temperature.
[0010] Preferably, the thermoplastic polyetherimide (PEI) contains ether bonds (-ROR) in its main chain and has a molecular weight between 40,000 and 60,000.
[0011] Preferably, the molecular weight of the epoxy-terminated polysiloxane (SiO) is between 400 and 700.
[0012] Preferably, the anhydride curing agent is a cyclic anhydride compound.
[0013] Preferably, the molecular weight of the cyclic anhydride compound is between 150 and 200.
[0014] Preferably, the mass ratio of thermoplastic polyetherimide (PEI), epoxy resin (EP), epoxy-terminated polysiloxane (SiO) and anhydride curing agent is 20-30:80-100:5-20:70-80.
[0015] The present invention also provides an organosilicon toughened epoxy resin prepared by the above preparation method.
[0016] To investigate the toughening mechanism of thermoplastic polyetherimide and organosilicon on epoxy resin, based on the above preparation method, we designed the following experimental scheme with the following raw material mass ratio:
[0017] Table 1. Mass ratio composition of pure EP and EP / SiO binary system blends
[0018]
[0019] The final phase structure of the EP / SiO system after phase separation was observed using scanning electron microscopy (SEM). The results showed that the phase structures formed after phase separation in the four studied systems did not exhibit significant differences. Figure 1 As shown in (a), its fracture surface is relatively smooth, exhibiting a typical brittle fracture morphology of epoxy resin; while... Figure 1 In (b) to (e), spherical particles can be observed to be uniformly dispersed within the epoxy matrix, and the particle size increases significantly with increasing organosilicon content (see the area marked by the red box in the upper right corner of each figure). Preliminary analysis indicates that the spherical particles are silicon spheres, presumably formed by the precipitation of organosilicon from the epoxy phase during phase separation.
[0020] To accurately determine the chemical composition of the dispersed phase in the phase-separated structure, energy-dispersive X-ray spectroscopy (EDS) analysis was performed on the fracture cross-section of the cured product. Two samples, EP / 10SiO and EP / 20SiO, were selected for EDS testing. In the figure, the red area represents carbon (C) element, corresponding to the epoxy resin phase; the green area represents silicon (Si) element, corresponding to the organosilicon phase. The color brightness reflects the content of the corresponding element.
[0021] Combination Figure 2 (a, a1, a2) and Figure 2 (b, b1, b2) clearly indicate that the spherical particles observed in the SEM images are the silicon phase, suggesting that during phase separation, the organosilicon is mainly dispersed in a spherical form within the epoxy matrix. Additionally, a small amount of organosilicon is distributed in the epoxy resin in a nearly homogeneous manner. This phenomenon is related not only to the compatibility between the organosilicon and epoxy phases but also to the curing reaction rate: if the reaction rate is too fast, some organosilicon cannot separate from the epoxy phase in time and will be solidified within the epoxy matrix during gelation.
[0022] Table 2. Specific values of tensile / shear strength and elongation at break of the EP / SiO system
[0023]
[0024] Analysis of the data in Table 2 shows that the introduction of organosilicon significantly improves both the tensile strength and elongation at break of the material. Specifically:
[0025] (1) The tensile strength of pure epoxy resin is 56.3 MPa. When the amount of organosilicon added is 10 parts, the tensile strength of the blend system reaches a maximum of 75.2 MPa, with an increase of 33.6%. However, as the organosilicon content further increases, the tensile strength decreases slightly. This may be because the introduction of excessive flexible silicon-oxygen bonds reduces the overall modulus of the material, thus having a negative impact on the tensile strength.
[0026] (2) The elongation at break of pure epoxy resin is 1.8%. When the amount of organosilicon added is 20 parts, the elongation at break of the blend system increases to 4.3%, an increase of 138.9%, indicating that the introduction of flexible segments significantly enhances the toughness of epoxy resin.
[0027] (3) The addition of organosilicon also significantly improved the shear strength of the material, increasing from 13.5 MPa for pure epoxy to 17.8 MPa for the EP / 15SiO system, an increase of 31.9%. This improvement may be attributed to two factors: first, the enhanced strength of the material itself led to the improvement of shear performance; second, the introduction of organosilicon enhanced the adhesion between the blend and the substrate.
[0028] In summary, the introduction of organosilicon can effectively improve the tensile and shear properties of epoxy resin, significantly enhancing the overall mechanical performance of the material.
[0029] To investigate the toughening mechanism of thermoplastic polyetherimide and organosilicon on epoxy resin, based on the above preparation method, we further designed the following experimental scheme with the following raw material mass ratio:
[0030] Table 3. Mass ratio composition of pure epoxy, EP / PEI, and EP / PEI / SiO blends
[0031]
[0032] Blends formed from epoxy resin and thermoplastic resin, when the two components are in appropriate proportions, exhibit phase separation following a reaction-induced phase separation (RIPS) mechanism. This means that as the curing reaction proceeds, the molecular weight of the epoxy prepolymer increases, leading to a mismatch in solubility parameters between the epoxy and thermoplastic phases, resulting in phase separation. This experiment used an optical microscope to record the phase structure evolution of the EP / PEI / SiO system during phase separation. Figure 3 The final phase structure of the EP / PEI / SiO system during isothermal curing at 150 ºC is shown.
[0033] Figure 3 (a) to (e) show the phase structure morphology of the EP / 25PEI, EP / 25PEI / 05SiO, EP / 25PEI / 10SiO, EP / 25PEI / 15SiO and EP / 25PEI / 20SiO systems, respectively. The bright areas are epoxy phases and the dark areas are PEI phases.
[0034] It can be observed that Figure 3 (a) It exhibits a typical bicontinuous phase structure, where the PEI phase and the epoxy phase interpenetrate and intertwine to form a continuous network. With the increase of organosilicon content ( Figure 3(b) to (c)), spherical precipitates appeared in both the bright area (epoxy phase) and the dark area (PEI phase). Based on previous analysis results, it can be inferred that these spherical particles are silicon phase. When the organosilicon content further increases ( Figure 3 From (d) to (e), the PEI phases gradually become more tightly connected, forming a more continuous matrix, while the epoxy phase is divided into isolated regions. At this time, the phase structure shows a trend of transformation from a bicontinuous phase to an inverted structure, that is, the originally less abundant PEI phase gradually transforms into a continuous matrix phase.
[0035] Table 4. Specific values of tensile / shear strength and elongation at break of the EP / PEI / SiO system
[0036]
[0037] Analysis of the data in Table 4 shows that the co-introduction of polyetherimide (PEI) and silicone resin has a significant impact on both the tensile strength and shear strength of epoxy resin. Specifically:
[0038] The tensile strength of the EP / 25PEI / 15SiO blend reached 77.9 MPa, an increase of 38.3% compared to pure epoxy resin (56.3 MPa); its elongation at break was 4.0%, an increase of 122.2% compared to pure epoxy; at the same time, the shear strength also increased from 13.5 MPa to 17.2 MPa, an increase of approximately 27.4%.
[0039] Furthermore, by comparing the EP / SiO system (Table 2) with the EP / PEI / SiO system (Table 4), the impact of PEI introduction on the performance of the EP / SiO system can be evaluated. Data shows that the addition of PEI can further improve the tensile strength of the EP / SiO system, but its effect on elongation at break and shear strength is relatively limited.
[0040] This phenomenon can be attributed to the following mechanism: PEI, as a high-performance thermoplastic polymer with a high glass transition temperature (Tg), can effectively enhance the rigidity and bulk strength of the blend, thereby improving tensile properties. The change in elongation at break is mainly affected by the system's flexibility, which in this experimental system is closely related to the content of organosilicon—within a certain range, the higher the organosilicon content, the greater the proportion of flexible segments, and the higher the elongation at break. Therefore, the introduction of PEI did not significantly promote the elongation at break.
[0041] Furthermore, shear strength depends not only on the bulk strength of the material but also on the adhesion of the blend to the substrate. Experimental results show that although the addition of PEI improves the bulk strength of the blend, it does not significantly enhance its interfacial adhesion to the substrate, and therefore fails to contribute further to the shear strength.
[0042] Based on the above research, this invention provides a composite system for synergistic toughening modification of epoxy resin by polyetherimide (PEI) and organosilicon resin, and its preparation method. Experimental results show that this ternary blend system exhibits significantly better mechanical properties than pure epoxy resin in terms of tensile strength, elongation at break, and shear strength.
[0043] Specifically, by controlling the organosilicon content, the phase structure can be effectively induced to evolve from a bicontinuous phase to an inverted phase, forming a microstructure with silicon spheres as the dispersed phase, thereby significantly improving the material's flexibility and elongation at break. Simultaneously, the introduction of PEI further enhances the bulk strength of the blend, resulting in an additional improvement in tensile properties. This composite system maintains high strength while also possessing good toughness and interfacial properties, exhibiting significantly superior overall mechanical properties compared to traditional binary toughened systems, thus possessing significant engineering application value.
[0044] The specific methods for characterizing the above materials are as follows:
[0045] Optical microscope (OM)
[0046] The optical microscope used in this invention is an SPL-50TF model with a magnification of 100x, equipped with a precision constant-temperature heating stage. The specific process is as follows: Two glass slides are placed on the heating stage. An uncured sample, refrigerated in a refrigerator, is taken out and a suitable amount of sample is dropped into the center of one of the glass slides. While covering the sample with the other glass slide, the sample is pressed into a thin film using tweezers, while simultaneously squeezing out any air that may be present in the sample. The glass slide is then placed on the constant-temperature heating stage, pre-set to 150 ºC, perpendicular to the lens, and image capture begins immediately. Capturing stops when the phase structure is fixed. The phase separation process of different systems is analyzed by reading the images at intervals.
[0047] Scanning electron microscope (SEM)
[0048] Microstructure and energy dispersive spectroscopy (EDS) analysis of the fracture sections of the samples were performed using an XL39 scanning electron microscope. Sample preparation: The fully solidified samples were subjected to low-temperature brittle fracture in liquid nitrogen, and samples with smooth fracture sections were retained. After gold sputtering, the microstructure and elemental distribution of the fracture sections were observed at an appropriate magnification.
[0049] Tensile testing machine
[0050] Mechanical testing of the materials was performed using a CZ-8000 servo-controlled tensile testing machine. For tensile strength testing, the tensile rate was 100 mm / min, and the sample shape was type II. For shear strength testing, the rate was 10 mm / min, the adhesive layer thickness was approximately 250 micrometers, the bonding area was 25 mm * 12.5 mm, and the substrate was 6061 aluminum.
[0051] Beneficial effects: This invention provides a novel method for preparing organosilicon toughened epoxy resin; studies have shown that the organosilicon toughened epoxy resin prepared by the method of this invention maintains high strength while also possessing good toughness and interfacial properties, and its comprehensive mechanical properties are significantly better than those of traditional binary toughening systems, thus possessing important engineering application value. Attached Figure Description
[0052] Figure 1 The final phase structure diagrams are shown for pure EP and EP / SiO binary system blends; where, Figure 1 (a) is the final phase structure diagram of pure EP; Figure 1 (b) is the final phase structure diagram of EP / 05SiO; Figure 1 (c) is the final phase structure diagram of EP / 10SiO; Figure 1 (d) is the final phase structure diagram of EP / 15SiO; Figure 1 (e) is the final phase structure diagram of EP / 20SiO.
[0053] Figure 2 SEM / EDS images of blends of the EP / SiO binary system; where, Figure 2 (a) is a SEM / EDS image of EP / 10SiO; Figure 2 (a1) is the C element image of EP / 10SiO; Figure 2 (a2) is the Si elemental image of EP / 10SiO; Figure 2 (b) is the SEM / EDS image of EP / 20SiO; Figure 2 (b1) is the C element image of EP / 20SiO; Figure 2 (b2) is the Si element image of EP / 20SiO.
[0054] Figure 3 The images show the final phase morphology of EP / PEI and EP / PEI / SiO blends; among them, Figure 3 (a) is the final phase morphology diagram of EP / 25PEI; Figure 3 (b) is the final phase morphology diagram of EP / 25PEI / 5SiO; Figure 3 (c) is the final phase morphology diagram of EP / 25PEI / 10SiO; Figure 3 (d) is the final phase morphology diagram of EP / 25PEI / 15SiO; Figure 3 (e) is the final phase morphology diagram of EP / 25PEI / 20SiO. Detailed Implementation
[0055] The present invention will be further described below with reference to the embodiments. The embodiments do not limit the scope of protection of the present invention in any way. All raw materials involved in this application can be purchased commercially.
[0056] The epoxy resin described in the following examples is epoxy resin of the brand name DER331 purchased from Dow Chemical.
[0057] The silicone described in the following examples was purchased from Gelest, USA, and is brand name DMS-E11.
[0058] The curing agent described in the following examples is HY806, purchased from Shandong Heyu Runfeng New Material Co., Ltd.
[0059] The polyetherimide described in the following examples is polyetherimide of grade UTEM-1000 purchased from Saudi Basic Industries Innovative Plastics Company, Saudi Arabia.
[0060] Example 1: Preparation of Organosilicon Toughened Epoxy Resin
[0061] Raw material composition by weight: 95 parts epoxy resin, 5 parts organosilicon, 78.7 parts curing agent, and 25 parts polyetherimide.
[0062] Preparation method: Weigh epoxy resin and polyetherimide in a beaker and place them on a preheated 150ºC constant temperature hot plate. Stir magnetically to completely dissolve the polyetherimide into the epoxy resin to obtain an epoxy / polyetherimide mixture. Then add silicone to the epoxy / polyetherimide mixture and stir at 150°C until uniformly mixed. Then transfer to a 120°C constant temperature hot plate, add curing agent, and stir until clear and free of stringing. Finally, pour it into a mold for curing. The curing process is as follows: pre-curing at 150ºC for 5 hours, followed by curing at 200ºC for 2 hours.
[0063] Example 2 Preparation of Organosilicon Toughened Epoxy Resin
[0064] Raw material composition by weight: 90 parts epoxy resin, 10 parts organosilicon, 77.4 parts curing agent, and 25 parts polyetherimide.
[0065] Preparation method: Weigh epoxy resin and polyetherimide in a beaker and place them on a preheated 150ºC constant temperature hot plate. Stir magnetically to completely dissolve the polyetherimide into the epoxy resin to obtain an epoxy / polyetherimide mixture. Then add silicone to the epoxy / polyetherimide mixture and stir at 150°C until uniformly mixed. Then transfer to a 120°C constant temperature hot plate, add curing agent, and stir until clear and free of stringing. Finally, pour it into a mold for curing. The curing process is as follows: pre-curing at 150ºC for 5 hours, followed by curing at 200ºC for 2 hours.
[0066] Example 3 Preparation of silicone-toughened epoxy resin
[0067] Raw material composition by weight: 85 parts epoxy resin, 15 parts silicone, 76.1 parts curing agent, and 25 parts polyetherimide.
[0068] Preparation method: Weigh epoxy resin and polyetherimide in a beaker and place them on a preheated 150ºC constant temperature hot plate. Stir magnetically to completely dissolve the polyetherimide into the epoxy resin to obtain an epoxy / polyetherimide mixture. Then add silicone to the epoxy / polyetherimide mixture and stir at 150°C until uniformly mixed. Then transfer to a 120°C constant temperature hot plate, add curing agent, and stir until clear and free of stringing. Finally, pour it into a mold for curing. The curing process is as follows: pre-curing at 150ºC for 5 hours, followed by curing at 200ºC for 2 hours.
[0069] Example 4 Preparation of Organosilicon Toughened Epoxy Resin
[0070] Raw material composition by weight: 80 parts epoxy resin, 20 parts organosilicon, 74.8 parts curing agent, and 25 parts polyetherimide.
[0071] Preparation method: Weigh epoxy resin and polyetherimide in a beaker and place them on a preheated 150ºC constant temperature hot plate. Stir magnetically to completely dissolve the polyetherimide into the epoxy resin to obtain an epoxy / polyetherimide mixture. Then add silicone to the epoxy / polyetherimide mixture and stir at 150°C until uniformly mixed. Then transfer to a 120°C constant temperature hot plate, add curing agent, and stir until clear and free of stringing. Finally, pour it into a mold for curing. The curing process is as follows: pre-curing at 150ºC for 5 hours, followed by curing at 200ºC for 2 hours.
Claims
1. A method for preparing an organosilicon toughened epoxy resin, characterized in that, The process includes the following steps: dissolving thermoplastic polyetherimide (PEI) in epoxy resin (EP), then adding epoxy-terminated polysiloxane (SiO), and stirring thoroughly to form an EP / PEI / SiO ternary blend system; then adding an acid anhydride curing agent, mixing evenly, and then carrying out a curing reaction under high temperature conditions. After the reaction is completed, an organosilicon toughened epoxy resin is obtained.
2. The method for preparing organosilicon toughened epoxy resin according to claim 1, characterized in that, The epoxy resin is a bisphenol A type epoxy resin.
3. The method for preparing organosilicon toughened epoxy resin according to claim 2, characterized in that, The epoxy equivalent of the bisphenol A type epoxy resin is 182-192 g / mol.
4. The method for preparing organosilicon toughened epoxy resin according to claim 1, characterized in that, The thermoplastic polyetherimide (PEI) is formed by the condensation polymerization of bisphenol A dianhydride and aromatic diamine at high temperature.
5. The method for preparing organosilicon toughened epoxy resin according to claim 4, characterized in that, The thermoplastic polyetherimide (PEI) contains ether bonds (-ROR) in its main chain and has a molecular weight between 40,000 and 60,000.
6. The method for preparing organosilicon toughened epoxy resin according to claim 1, characterized in that, The molecular weight of the epoxy-terminated polysiloxane (SiO) is between 400 and 700.
7. The method for preparing organosilicon toughened epoxy resin according to claim 1, characterized in that, The acid anhydride curing agent is a cyclic acid anhydride compound.
8. The method for preparing organosilicon toughened epoxy resin according to claim 7, characterized in that, The molecular weight of the cyclic anhydride compound is between 150 and 200.
9. The method for preparing organosilicon toughened epoxy resin according to claim 1, characterized in that, The mass ratio of thermoplastic polyetherimide (PEI), epoxy resin (EP), epoxy-terminated polysiloxane (SiO) and acid anhydride curing agent is 20-30:80-100:5-20:70-80.
10. The organosilicon toughened epoxy resin prepared by the preparation method according to any one of claims 1-9.