Ternary-particle-size nanometer aluminum oxide / epoxy resin composite material and preparation method thereof
By mixing ternary alumina nanoparticles with fillers and epoxy resin, a uniformly dispersed composite material is formed, which solves the problem of high thermal expansion coefficient of epoxy resin, achieves good thermomechanical stability and flowability with low filler content, facilitates processing and molding, and improves the stability and lifespan of aerospace devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTH CHINA ELECTRIC POWER UNIV
- Filing Date
- 2026-03-19
- Publication Date
- 2026-05-01
AI Technical Summary
Existing epoxy resins used in electrical and electronic components in aerospace and other fields have a high coefficient of thermal expansion, which leads to poor heat diffusion and thermal stress concentration, affecting the stability and lifespan of the devices. In addition, high filler content leads to increased viscosity and deterioration of flowability, making them difficult to mold.
A composite filler consisting of ternary alumina nanoparticles is prepared and mixed with epoxy resin after surface modification to form a uniformly dispersed composite material. Alumina nanoparticle I forms the main framework, alumina nanoparticle II fills the gaps between large particles, and alumina nanoparticle III fills the micropores to form a dense contact network.
At low filler content, the composite material maintains good thermomechanical stability and flowability, making it easy to process and mold. The coefficient of thermal expansion is reduced by about 10%, which improves the stability and service life of the device.
Smart Images
Figure CN121949979A_ABST
Abstract
Description
A ternary particle size nano-alumina / epoxy resin composite material and its preparation method Technical Field
[0001] This invention belongs to the technical field of alumina-epoxy resin composite materials, specifically relating to a ternary particle size nano-alumina / epoxy resin composite material and its preparation method. Background Technology
[0002] Epoxy resins are an important class of thermosetting polymers, widely used in polymer composites due to their excellent electrical insulation, chemical resistance, mechanical properties, and low shrinkage. However, in electrical and electronic component applications in aerospace and other fields, the inherently high coefficient of thermal expansion of epoxy resins can easily lead to problems such as poor heat diffusion and thermal stress concentration during operation, thus affecting the stability and service life of the devices.
[0003] To improve the thermal properties of epoxy resins, a common method is to modify them through composite modification by introducing fillers, such as silica, carbon nanotubes, alumina, and graphene. Among these, micron-sized alumina fillers, due to their strong chemical bonds and highly ordered crystal structure, exhibit a low coefficient of thermal expansion (approximately 7 × 10⁻⁶). -6 This property ( / ℃) allows alumina to maintain the thermomechanical stability of the material. However, this method still faces some problems: controlling the coefficient of thermal expansion in the resin often requires a high filler content, which leads to a sharp increase in system viscosity and deterioration in flowability, making the molding process difficult; while at low filler content, the coefficient of thermal expansion of the composite material is also difficult to meet the requirements of the application environment. Summary of the Invention
[0004] The purpose of this invention is to provide a ternary particle size nano-alumina / epoxy resin composite material and its preparation method; the method uses ternary particle size nano-alumina particles as filler, which can maintain good thermomechanical stability of the composite material at a low filling amount, and has good flowability and plasticity, making it easy to process and mold.
[0005] To achieve the above objectives, the present invention provides the following technical solutions: (1) Surface modification treatment is performed on three nano-alumina particles I, II, and III with different average particle size distributions to obtain modified nano-alumina particles I, II, and III, and then they are mixed in a certain weight ratio to obtain modified ternary nano-alumina composite filler; the average particle sizes of the nano-alumina particles I, II, and III are 400-4000 nm, 40-100 nm, and 5-15 nm, respectively; the mass ratio between the modified nano-alumina particles I, II, and III is (3-18):(1-4):1; (2) Epoxy resin, modified ternary nano-alumina composite filler, and curing agent are mixed, and a composite slurry is obtained by stirring and vacuum degassing; (3) The composite slurry is cured and molded to obtain a ternary nano-alumina / epoxy resin composite material.
[0006] Preferably, in step (1), the surface modification treatment is as follows: a certain volume ratio of silane coupling agent is mixed with an ethanol aqueous solution and the pH is adjusted with glacial acetic acid. After mixing evenly, a modified solution is obtained. Then, nano alumina particles I, nano alumina particles II, and nano alumina particles III are added to the modified solution respectively. After stirring in a water bath, they are centrifuged, washed, vacuum dried, and ground in sequence to obtain modified nano alumina particles I, modified nano alumina particles II, and modified nano alumina particles III.
[0007] Preferably, the silane coupling agent is one or more of KH550, KH560, and KH602.
[0008] Preferably, the volume percentage of ethanol in the aqueous ethanol solution is 90-95%; the volume ratio of silane coupling agent to aqueous ethanol solution is 1:(19-29).
[0009] Preferably, the pH is adjusted to 4-5 by glacial acetic acid; the ratio of nano-alumina particles to modified solution is 1g:(9-12)ml; and the water bath temperature is 60-80℃.
[0010] Preferably, in step (1), the stirring is mechanical stirring, the stirring speed is 200-400 r / min, and the stirring time is 2-4 h; the vacuum drying temperature is 110-140℃, and the vacuum drying time is 5-8 h.
[0011] Preferably, in step (2), the mass ratio between the modified ternary nano-alumina composite filler and the epoxy resin is 3:2; the amount of curing agent added is 3-6% of the mass of the epoxy resin; the curing agent is any one or more of EMI-2,4, DMP-10, and DMP-20; and the epoxy resin is YDF-170.
[0012] Preferably, in step (2), the stirring is mechanical stirring, the stirring speed is 200-400 r / min, the stirring time is 2-3 h, and the vacuum degassing time is 30-60 min.
[0013] Preferably, in step (3), the curing time is 6-8 hours and the curing temperature is 110-150℃.
[0014] To achieve the above-mentioned objectives, the present invention also provides a ternary particle size nano-alumina / epoxy resin composite material prepared by the above-mentioned preparation method.
[0015] Compared with existing technologies, this invention has the following advantages: 1. The fillers used in this invention are all alumina, which significantly reduces costs compared to materials such as aluminum nitride and boron nitride, and is also easier to achieve uniform dispersion in the epoxy resin matrix; 2. This invention uses ternary alumina particles for compounding, wherein nano-alumina particles I form the main framework, nano-alumina particles II effectively fill the gaps between large particles, and nano-alumina particles III further fill the residual micropores, making the filler distribution more uniform; moreover, the mass ratio is close to the optimal packing state, giving the composite material good flowability and plasticity, and facilitating processing and molding; 3. The introduction of nano-alumina particles III with a particle size of less than 50 nm in this invention allows for the formation of a large number of interface layers between the particles and the epoxy resin at a low content, effectively constraining the movement of polymer molecular chains, thereby significantly reducing the coefficient of thermal expansion of the composite material; at a 30% volume fraction filling, its coefficient of thermal expansion is 39.726 × 10⁻⁶. -6 The temperature is reduced by about 10% compared to the single nano-alumina particle I filling system, and the thermomechanical stability is improved. Attached Figure Description
[0016] Figure 1 shows SEM images of the fracture surfaces of the composite materials prepared in the comparative examples and Examples 1 to 3 of the present invention: (a) Comparative Example 1; (b) Example 1; (c) Example 2; (d) Example 3; Figure 2 shows the relative densities of the composite materials prepared in the comparative examples and Examples 1 to 3 of the present invention; Figure 3 shows the coefficients of thermal expansion of the composite materials prepared in the comparative examples and Examples 1 to 3 of the present invention in the glass and rubber states. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments and comparative examples. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0018] A comparative example of a method for preparing a single-particle-size nano-alumina / epoxy resin composite material includes the following steps: (1) Measure 190 ml of 95% ethanol aqueous solution, add 10 mL of silane coupling agent KH560, adjust the pH to 4 with glacial acetic acid, mix evenly to allow KH560 to be fully hydrolyzed to obtain a modified solution; according to the ratio of nano-alumina particles to modified solution of 1 g: 9 ml, add 22 g of nano-alumina particles I (average particle size of 400 nm) to the modified solution, and then place it in an 80°C water bath and mechanically heat it at 400 r / min. (1) Stir for 4 hours to carry out condensation reaction; after the reaction is completed, centrifuge, wash, vacuum dry at 140℃ for 8 hours and grind to obtain modified nano alumina particles I; (2) Weigh 40g of YDF-170 epoxy resin, add 60g of modified nano alumina particles I and 1.2g of curing agent EMI-2,4, and mechanically stir at 200r / min for 3 hours to make it evenly mixed. Then place the mixture in a vacuum drying oven to degas for 30 minutes to obtain composite slurry; (3) Place the composite slurry in a drying oven at 150℃ to cure for 8 hours to obtain single-particle-size nano alumina / epoxy resin composite material.
[0019] Example 1: A method for preparing a ternary particle size nano-alumina / epoxy resin composite material, comprising the following steps: (1) Measure 290 ml of 90% ethanol aqueous solution, add 10 mL of silane coupling agent KH560, adjust the pH to 5 with glacial acetic acid, mix evenly to allow KH560 to be fully hydrolyzed to obtain a modified solution; according to the ratio of nano-alumina particles to modified solution of 1 g: 12 ml, add 25 g of nano-alumina particles I (average particle size of 4000 nm) to the modified solution, and then place it in an 80°C water bath and mechanically stir at 400 r / min for 4 h to carry out a condensation reaction; after the reaction is completed, centrifuge, wash, vacuum dry at 140°C for 8 h and grind to obtain modified nano-alumina particles I; the modification process of nano-alumina particles II (average particle size of 100 nm) and nano-alumina particles III (average particle size of 15 nm) is the same as that of nano-alumina particles I. (1) Modified nano alumina particles I, modified nano alumina particles II, and modified nano alumina particles III were mixed in a mass ratio of 9:0.5:0.5 to obtain modified ternary nano alumina composite filler; (2) 40g of YDF-170 epoxy resin was weighed, 60g of modified ternary nano alumina composite filler and 2.4g of curing agent DMP-10 were added, and the mixture was mechanically stirred at 400r / min for 3h to make it uniform. Then the mixture was placed in a vacuum drying oven for degassing for 60min to obtain a composite slurry; (3) The composite slurry was placed in a 150℃ drying oven for curing for 8h to obtain a ternary nano alumina / epoxy resin composite material.
[0020] Example 2: A method for preparing a ternary particle size nano-alumina / epoxy resin composite material, comprising the following steps: (1) Measure 190 ml of 95% ethanol aqueous solution, add 10 mL of silane coupling agent KH550, adjust the pH to 4 with glacial acetic acid, mix evenly to allow KH550 to be fully hydrolyzed to obtain a modified solution; according to the ratio of nano-alumina particles to modified solution of 1 g: 9 ml, add 22 g of nano-alumina particles I (average particle size of 400 nm) to the modified solution, and then place it in a 60°C water bath and mechanically stir at 200 r / min for 2 h to carry out a condensation reaction; after the reaction is completed, centrifuge, wash, vacuum dry at 110°C for 5 h and grind to obtain modified nano-alumina particles I; the modification process of nano-alumina particles II (average particle size of 40 nm) and nano-alumina particles III (average particle size of 5 nm) is the same as that of nano-alumina particles I. (1) Modified nano alumina particles I, modified nano alumina particles II, and modified nano alumina particles III were mixed in a mass ratio of 7.5:2:0.5 to obtain modified ternary nano alumina composite filler; (2) 40g of YDF-170 epoxy resin was weighed, 60g of modified ternary nano alumina composite filler and 1.2g of curing agent EMI-2,4 were added, and the mixture was mechanically stirred at 200r / min for 2h to make it uniform. Then the mixture was placed in a vacuum drying oven for degassing for 30min to obtain a composite slurry; (3) The composite slurry was placed in a 110℃ drying oven for curing for 6h to obtain a ternary nano alumina / epoxy resin composite material.
[0021] Example 3 A method for preparing a ternary particle size nano-alumina / epoxy resin composite material includes the following steps: (1) Measure 210 ml of 92% ethanol aqueous solution, add 10 mL of silane coupling agent KH602, adjust the pH to 4.5 with glacial acetic acid, mix evenly to fully hydrolyze KH602 to obtain a modified solution; according to the ratio of nano-alumina particles to modified solution of 1 g: 10 ml, add 22 g of nano-alumina particles I (average particle size of 800 nm) to the modified solution, and then place it in a 70°C water bath and mechanically stir at 300 r / min for 3 h to carry out a condensation reaction; after the reaction is completed, centrifuge, wash, vacuum dry at 120°C for 6 h and grind to obtain modified nano-alumina particles I; the modification process of nano-alumina particles II (average particle size of 40 nm) and nano-alumina particles III (average particle size of 5 nm) is the same as that of nano-alumina particles I. (1) Modified nano alumina particles I, modified nano alumina particles II, and modified nano alumina particles III were mixed in a mass ratio of 6:2:2 to obtain modified ternary nano alumina composite filler; (2) 40g of YDF-170 epoxy resin was weighed, 60g of modified ternary nano alumina composite filler and 2g of curing agent DMP-20 were added, and the mixture was mechanically stirred at 300r / min for 2h to make it uniform. Then the mixture was placed in a vacuum drying oven for degassing for 40min to obtain a composite slurry; (3) The composite slurry was placed in a 130℃ drying oven for curing for 7h to obtain a ternary nano alumina / epoxy resin composite material.
[0022] Material characterization and performance testing were performed on the alumina / epoxy resin composite materials prepared in Comparative Example 1 and Examples 1 to 3 respectively. The specific results are as follows: 1. Microstructure and Density: The samples of Comparative Example 1 and Examples 1 to 3 were subjected to fracture treatment, and conductive adhesive was used to fix the fractured samples on the substrate to maintain stability. Subsequently, gold sputtering was performed to increase the conductivity of the samples, and then the microstructure of the fracture surface of the test samples was characterized by field emission ultra-high resolution scanning electron microscopy (SEM), as shown in Figure 1. In Comparative Example 1, the modified nano-alumina particles I were relatively uniformly dispersed in the epoxy resin matrix, and a continuous contact network could be formed between the particles. In Example 1, the modified nano-alumina particles I could still maintain good dispersion, while a small amount of modified nano-alumina particles II and III were scattered in between, which enhanced the contact network. In Example 2, the modified nano-alumina particles II and III accounted for 25% of the total filler mass. This proportion is close to the theoretical maximum filling density of the composite filler system, and the interparticle spacing is small. Microscopic morphology analysis shows that small-sized particles effectively fill the gaps between large particles, forming a dense and interconnected contact network among the three particle sizes. In Example 3, although the uniformity of modified nano-alumina particles I decreased, the increase in modified nano-alumina particles II and III resulted in a better contact network between the particles.
[0023] Furthermore, compared to Comparative Example 1, the surface roughness of the cracks in Examples 1 to 3 gradually increased, indicating that their mechanical properties gradually improved. This is mainly because as the mass fraction of modified nano-alumina particles II and III increased, the density of obstacles per unit volume increased, increasing the probability of deflection during crack propagation. At the same time, the increase in the specific surface area of the filler enhanced the interfacial interaction between it and the matrix, further promoting crack deflection and interfacial debonding, thus macroscopically manifesting as an increase in surface roughness.
[0024] The density of Comparative Example 1 and Examples 1 to 3 was measured using the mass-volume method, as shown in Figure 2. It can be seen that the relative density of Examples 1 to 3 is slightly lower than that of Comparative Example 1. Furthermore, the relative density of the composite material decreases slightly with increasing mass fractions of modified nano-alumina particles II and III. This is because the small-diameter particles with a large specific surface area significantly increase the viscosity of the epoxy resin mixture, making it difficult for air bubbles to escape during curing, thus leaving more micropores inside the composite material. Nevertheless, the density of all samples remains relatively high, with relative densities all exceeding 98.24%.
[0025] 2. Thermal Expansion Properties: The coefficients of thermal expansion of the alumina / epoxy resin composites of Comparative Examples 1 to 3 and Examples 1 to 3 were measured using a thermomechanical analyzer SDTA2+ at a heating rate of 2°C / min. The thermal expansion properties of the composites in the glassy state (30-80°C) and rubbery state (160-200°C) were analyzed, and the results are shown in Figure 3. Comparative Example 1 showed the highest coefficients of thermal expansion in both the glassy and rubbery states, at 44.846 × 10⁻⁶. -6 / ℃ and 125.438×10 -6 / ℃. With the increase of the filling ratio of modified nano-alumina particles II and III, the coefficient of thermal expansion showed a trend of first decreasing and then increasing, but both were lower than that of Comparative Example 1. Example 2 had the lowest coefficient of thermal expansion, with coefficients of thermal expansion of 39.726 × 10⁻⁶ in both the glass and rubber states. -6 / ℃ and 111.028×10 -6 / ℃, which is about 10% lower than that of the control group.
[0026] Compared to Comparative Example 1, Example 1, due to the introduction of a small amount of modified nano-alumina particles III, significantly increases the volume fraction of the interfacial layer formed between the alumina and epoxy resins due to their extremely large specific surface area. This interfacial layer effectively constrains the movement of polymer molecular chains, thereby reducing the coefficient of thermal expansion of the composite material. In Example 2, modified nano-alumina particles 1 constitute the main framework, modified nano-alumina particles II effectively fill the gaps between large particles, and the lower content of modified nano-alumina particles III suppresses their tendency to agglomerate due to their high surface energy. Therefore, they can be better dispersed and filled in the micropores remaining in the particles, forming a uniform filler distribution. This ratio is close to the optimal packing state, forming a dense and continuous filler network that greatly restricts the thermal movement of the matrix molecular chain segments, resulting in the lowest coefficient of thermal expansion. In Example 3, excessive modified nano-alumina particles III are prone to agglomeration. The resulting agglomerates disrupt the continuity of the large particle framework, weakening the inhibitory effect on thermal expansion. However, because they form a larger interfacial layer, the constraint on molecular chain movement still dominates, thus maintaining a low coefficient of thermal expansion.
Claims
1. A method for preparing a ternary particle size nano-alumina / epoxy resin composite material, characterized in that, The process includes the following steps: (1) Surface modification treatment of three nano-alumina particles I, II, and III with different average particle size distributions is performed to obtain modified nano-alumina particles I, II, and III, which are then mixed in a certain weight ratio to obtain modified ternary nano-alumina composite filler; the average particle sizes of the nano-alumina particles I, II, and III are 400-4000 nm, 40-100 nm, and 5-15 nm, respectively; the mass ratio of the modified nano-alumina particles I, II, and III is (3-18):(1-4):1; (2) Epoxy resin, modified ternary nano-alumina composite filler, and curing agent are mixed, and a composite slurry is obtained by stirring and vacuum degassing; (3) The composite slurry is cured and molded to obtain a ternary nano-alumina / epoxy resin composite material.
2. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 1, characterized in that, In step (1), the surface modification treatment is as follows: a certain volume ratio of silane coupling agent is mixed with an ethanol aqueous solution and the pH is adjusted with glacial acetic acid. After mixing evenly, a modified solution is obtained. Then, nano alumina particles I, nano alumina particles II, and nano alumina particles III are added to the modified solution respectively. After stirring in a water bath, they are centrifuged, washed, vacuum dried, and ground in sequence to obtain modified nano alumina particles I, modified nano alumina particles II, and modified nano alumina particles III.
3. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 2, characterized in that, The silane coupling agent is one or more of KH550, KH560, and KH602.
4. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 2, characterized in that, The volume percentage of ethanol in the aqueous ethanol solution is 90-95%; the volume ratio of silane coupling agent to aqueous ethanol solution is 1:(19-29).
5. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 2, characterized in that, The pH was adjusted to 4-5 with glacial acetic acid; the ratio of nano-alumina particles to modified solution was 1g:(9-12)ml; and the water bath temperature was 60-80℃.
6. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 2, characterized in that, In step (1), the stirring is mechanical stirring, the stirring speed is 200-400 r / min, and the stirring time is 2-4 h; the vacuum drying temperature is 110-140℃, and the vacuum drying time is 5-8 h.
7. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 1 or 2, characterized in that, In step (2), the mass ratio between the modified ternary nano-alumina composite filler and the epoxy resin is 3:2; the amount of curing agent added is 3-6% of the mass of the epoxy resin; the curing agent is any one or more of EMI-2,4, DMP-10, and DMP-20; and the epoxy resin is YDF-170.
8. The method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 1 or 2, characterized in that, In step (2), the stirring is mechanical stirring, the stirring speed is 200-400 r / min, the stirring time is 2-3 h; the vacuum degassing time is 30-60 min.
9. A method for preparing a ternary particle size nano-alumina / epoxy resin composite material according to claim 1 or 2, characterized in that, In step (3), the curing time is 6-8 hours and the curing temperature is 110-150℃.
10. The ternary particle size nano-alumina / epoxy resin composite material prepared by the preparation method according to any one of claims 1-9.