Modified boron nitride-epoxy resin composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of thermal management materials, and particularly relates to a modified boron nitride-epoxy resin composite material and a preparation method and application thereof. The modified boron nitride-epoxy resin composite material provided by the invention comprises an epoxy resin matrix and a heat-conducting filler dispersed in the epoxy resin matrix, the heat conduction filler comprises glycine modified boron nitride and magnetic modified boron nitride nanosheets, and the magnetic modified boron nitride nanosheets are glycine modified boron nitride nanosheets coated with ferroferric oxide particles. According to the invention, glycine modified boron nitride and magnetic modified boron nitride nanosheets are adopted as heat-conducting fillers, so that the interface interaction is enhanced, the dispersity of the boron nitride fillers in an epoxy resin matrix is improved, and the heat-conducting fillers form a filler network with a three-dimensional structure in the epoxy resin matrix, so that free transmission of phonons is facilitated; therefore, the heat conductivity of the modified boron nitride-epoxy resin composite material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal management materials, and particularly relates to a modified boron nitride-epoxy resin composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As a kind of thermal management materials, thermal interface materials are widely used in electronic devices. With the development of 5G technology and electronic packaging technology, electronic components such as chips are continuously developing towards miniaturization and high integration, resulting in continuous improvement of power and heat flux density. The heat accumulated in electronic devices cannot be dissipated in time, which has become a key factor restricting the development of electronic products. An ideal thermal interface material should have high thermal conductivity, excellent electrical insulation, good thermal stability, and low cost. Polymer-based composite materials have become one of the popular thermal management interface materials due to their flexibility, light weight, insulation, and good mechanical properties. Among them, epoxy resin (EP) is widely used as a matrix in the field of thermal interface materials due to its good compatibility with various materials.

[0003] At present, the main ways to improve the thermal conductivity of epoxy resin are to add thermal conductive fillers with high thermal conductivity and form a three-dimensional thermal conductive network. Hexagonal boron nitride (h-BN) has a layered crystal structure, and the in-plane thermal conductivity can reach 300 W / (m·K). The in-plane thermal conductivity of boron nitride nanosheets (BNNS) obtained by exfoliating h-BN can reach 1700 - 2000 W / (m·K), and the dielectric strength is 35 kV / mm. It has excellent thermal conductivity and electrical insulation, and is an ideal thermal conductive filler. However, when directly adding h-BN or BNNS into the epoxy resin matrix, the dispersion of h-BN or BNNS is poor, phonon scattering is serious, which is not conducive to the effective transfer of heat; moreover, h-BN or BNNS cannot form a three-dimensional thermal conductive network in the epoxy resin matrix. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified boron nitride-epoxy resin composite material, a preparation method thereof, and an application thereof. In the modified boron nitride-epoxy resin composite material provided by the present invention, the thermal conductive fillers are uniformly dispersed, and the thermal conductive fillers form a three-dimensional structural filler network in the epoxy resin matrix, which can improve the thermal conductivity of the modified boron nitride-epoxy resin composite material.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A modified boron nitride-epoxy resin composite material, comprising an epoxy resin matrix and thermal conductive fillers dispersed in the epoxy resin matrix; the thermal conductive fillers include glycine-modified boron nitride and magnetically modified boron nitride nanosheets, and the magnetically modified boron nitride nanosheets are glycine-modified boron nitride nanosheets coated with magnetite particles.

[0007] Preferably, the mass of the thermal conductive filler is 10-40% of the mass of the modified boron nitride-epoxy resin composite; the mass ratio of glycine-modified boron nitride to magnetically modified boron nitride nanosheets is 1-2:1-3.

[0008] Preferably, the thickness of the glycine-modified boron nitride is 100-300 nm, and the in-plane size is 5-10 μm; the thickness of the magnetically modified boron nitride nanosheets is 1-5 nm, and the in-plane size is 300-5000 nm. The particle size of the magnetite particles on the magnetically modified boron nitride nanosheets is 50-2000 nm.

[0009] Preferably, the epoxy resin matrix is formed by curing epoxy resin in the presence of a curing agent; the epoxy resin includes bisphenol F resin; the curing agent includes amine curing agent; the mass ratio of the epoxy resin to the curing agent is 9-16:4.

[0010] The present invention provides a method for preparing the modified boron nitride-epoxy resin composite described in the above technical solution, including the following steps:

[0011] Mix epoxy resin, thermal conductive filler and curing agent to obtain a mixed dispersion;

[0012] Form the mixed dispersion under the condition of an external magnetic field to obtain a formed body;

[0013] Cure the formed body to obtain the modified boron nitride-epoxy resin composite.

[0014] Preferably, the intensity of the external magnetic field is 200-800 GS, and the forming includes tape casting.

[0015] Preferably, during the tape casting process, the direction of the external magnetic field is perpendicular to the direction of the tape used for tape casting.

[0016] Preferably, the curing includes first curing and second curing in sequence; the temperature of the first curing is 50-60 °C, and the time is 3-5 h; the temperature of the second curing is 20-30 °C, and the time is 8-10 h.

[0017] Preferably, the mixing includes: first mixing epoxy resin and thermal conductive filler to obtain a first mixture; second mixing the first mixture and the curing agent to obtain a mixed dispersion.

[0018] The present invention provides the application of the modified boron nitride-epoxy resin composite described in the above technical solution or the modified boron nitride-epoxy resin composite prepared by the preparation method as a thermal interface material in electronic devices.

[0019] The present invention provides a modified boron nitride-epoxy resin composite, which includes an epoxy resin matrix and a heat-conducting filler dispersed in the epoxy resin matrix; the heat-conducting filler includes glycine-modified boron nitride and magnetically modified boron nitride nanosheets, and the magnetically modified boron nitride nanosheets are glycine-modified boron nitride nanosheets coated with magnetite particles. The present invention uses glycine-modified boron nitride and magnetically modified boron nitride nanosheets as heat-conducting fillers, enhancing the interfacial interaction and improving the dispersion of boron nitride fillers in the epoxy resin matrix; the glycine-modified boron nitride and magnetically modified boron nitride nanosheets form a three-dimensional filler network in the epoxy resin matrix, which is beneficial to the free transmission of phonons. The interplanar thermal conductivity of the modified boron nitride-epoxy resin composite prepared by the present invention is 0.982 - 1.841 W / (m·K), and the in-plane thermal conductivity is 4.278 - 5.606 W / (m·K).

[0020] The present invention provides a preparation method for a modified boron nitride-epoxy resin composite. The present invention performs molding under the condition of the presence of an external magnetic field. The external magnetic field can orient the magnetically modified boron nitride nanosheets, which is beneficial to improving the thermal conductivity of the obtained modified boron nitride-epoxy resin composite.

[0021] Furthermore, the present invention uses magnetic field-assisted casting molding. The casting molding enables the glycine-modified boron nitride to be oriented parallel to the casting tape, and the external magnetic field can orient the magnetically modified boron nitride nanosheets perpendicular to the casting tape, constructing a three-dimensional filler network, which is beneficial to the free transmission of phonons and improves the thermal conductivity of the obtained modified boron nitride-epoxy resin composite. Description of the Drawings

[0022] Figure 1 Schematic diagram for preparing a modified boron nitride-epoxy resin composite by using magnetic field-assisted casting molding;

[0023] Figure 2 SEM image of the modified boron nitride-epoxy resin composite in Example 1. Detailed Embodiments

[0024] The present invention provides a modified boron nitride-epoxy resin composite (3DGly-BN / Fe3O4@BNNS / EP composite), which includes an epoxy resin matrix and a heat-conducting filler dispersed in the epoxy resin matrix; the heat-conducting filler includes glycine-modified boron nitride (Gly-BN) and magnetically modified boron nitride nanosheets (Fe3O4@BNNS), and the magnetically modified boron nitride nanosheets are glycine-modified boron nitride nanosheets coated with magnetite particles.

[0025] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well-known to those skilled in the art.

[0026] The modified boron nitride-epoxy resin composite provided by the present invention includes an epoxy resin matrix.

[0027] As an embodiment of the present invention, the epoxy resin matrix is formed by curing epoxy resin in the presence of a curing agent; the mass ratio of the epoxy resin to the curing agent is 9-16:4, specifically 12:4; the epoxy resin includes bisphenol F resin; the epoxy equivalent of the epoxy resin is 170; the epoxy resin is purchased from Chuzhou Huisheng Electronic Materials Co., Ltd.; the curing agent includes an amine curing agent, and in a specific embodiment of the present invention, the curing agent is curing agent 5010B.

[0028] The modified boron nitride-epoxy resin composite provided by the present invention includes a heat-conducting filler dispersed in the epoxy resin matrix; the heat-conducting filler includes glycine-modified boron nitride and magnetically modified boron nitride nanosheets, and the magnetically modified boron nitride nanosheets are glycine-modified boron nitride nanosheets coated with magnetite particles.

[0029] As an embodiment of the present invention, the heat-conducting filler is 10-40% of the mass of the modified boron nitride-epoxy resin composite, specifically 30%; the mass ratio of glycine-modified boron nitride to magnetically modified boron nitride nanosheets in the heat-conducting filler is 16:32-20, specifically 16:32, 16:24 or 16:20; the thickness of the glycine-modified boron nitride is 100-300 nm, specifically 240 nm, and the in-plane size is 5-10 μm; the thickness of the magnetically modified boron nitride nanosheets is 1-5 nm, and the in-plane size is 300-5000 nm. The particle size of the magnetite particles on the magnetically modified boron nitride nanosheets is 50-2000 nm. Glycine molecules are grafted onto boron nitride through B-C bonds, and the active groups carboxyl and amino in glycine molecules improve their dispersibility in the epoxy resin matrix. The magnetically modified boron nitride nanosheets are small in size and thin in thickness. Before the coating of magnetite particles, glycine molecules will be destroyed to form free hydroxyl and amino groups, and the smaller molecular weight hydroxyl and amino groups are grafted onto the nanosheets as active groups to enhance the binding with epoxy resin.

[0030] The heat-conducting filler of the present invention is dispersed in the epoxy resin matrix. As an embodiment of the present invention, the glycine-modified boron nitride and the magnetically modified boron nitride nanosheets form a three-dimensional network structure in the epoxy resin matrix.

[0031] As an embodiment of the present invention, the preparation method of the glycine-modified boron nitride includes the following steps:

[0032] Mix hexagonal boron nitride and glycine (Gly), and perform ball milling modification to obtain a mixed powder;

[0033] Mix the mixed powder with a dispersant, subject the resulting dispersion liquid to ultrasonic treatment and then standing in sequence, and then perform solid-liquid separation to obtain the glycine-modified boron nitride.

[0034] In the present invention, hexagonal boron nitride and glycine are mixed and subjected to ball milling modification to obtain a mixed powder. As an embodiment of the present invention, the mass ratio of the hexagonal boron nitride to glycine can be 1:2 to 4, specifically 1:3; the ball milling modification can be wet milling, the grinding aid used for the wet milling can be water, specifically deionized water, and the mass ratio of the hexagonal boron nitride to the grinding aid can be 1:10 to 15, specifically 1:12; the rotation speed of the wet milling can be 400 rpm, and the time can be 6 to 12 h, specifically 10 to 12 h. As an embodiment of the present invention, preferably, after the wet milling, vacuum filtration and washing are sequentially performed to obtain a mixed powder; the present invention has no special limitation on the vacuum filtration, and the present invention uses vacuum filtration to remove the grinding aid; the detergent used for the washing can be water, and the water can be deionized water, and the present invention has no special limitation on the washing, and the present invention removes the excess glycine by washing.

[0035] After obtaining the mixed powder, in the present invention, the mixed powder is mixed with a dispersant, the resulting dispersion liquid is subjected to ultrasonic treatment and then standing in sequence, and then solid-liquid separation is performed to obtain the glycine-modified boron nitride. As an embodiment of the present invention, the dispersant is isopropyl alcohol and water, and the volume ratio of the isopropyl alcohol to water can be 1:1; the concentration of the mixed powder in the dispersion liquid can be 10 mg / mL; the ultrasonic time is 5 to 8 h, specifically 6 h; the standing time can be 12 to 18 h, specifically 12 to 14 h; the temperature is 20 to 30 °C, specifically 25 °C. The present invention uses ultrasonic treatment to further exfoliate BN.

[0036] As an embodiment of the present invention, the method of solid-liquid separation can be standing separation; after the solid-liquid separation, a precipitate and a supernatant are obtained respectively, the precipitate is the glycine-modified boron nitride; the supernatant is a dispersion liquid of glycine-modified boron nitride nanosheets, and the dispersion liquid of glycine-modified boron nitride nanosheets can be used to prepare the magnetically modified boron nitride nanosheets, which will be described in detail below.

[0037] As an embodiment of the present invention, the preparation method of the magnetically modified boron nitride nanosheets includes the following steps:

[0038] Perform a first mixing of the dispersion liquid of the glycine-modified boron nitride nanosheets with polyvinylpyrrolidone to obtain a first mixed dispersion liquid;

[0039] The first mixed dispersion, FeCl3·6H2O, FeCl2·4H2O, NaOH solution and ethanol are mixed for coating modification treatment to obtain the magnetically modified boron nitride nanosheets.

[0040] In the present invention, the glycine-modified boron nitride nanosheet dispersion is first mixed with polyvinylpyrrolidone to obtain a first mixed dispersion. As an embodiment of the present invention, the first mixing is preferably carried out under magnetic stirring conditions. The rotation speed of the first mixing can be 600 rpm, and the time can be 1-2 h, specifically 1-1.5 h. As an embodiment of the present invention, the glycine-modified boron nitride nanosheet dispersion is preferably heated and concentrated, and the obtained concentrated solution is first mixed with polyvinylpyrrolidone; the temperature of the heating and concentration is 150-200 °C; the volume ratio of the concentrated solution to the glycine-modified boron nitride nanosheet dispersion can be 1:10; the present invention preferably ultrasonically disperses the concentrated solution and then first mixes it with polyvinylpyrrolidone, and the time of the ultrasonic dispersion is 10-20 min, specifically 10-15 min. The present invention heats and concentrates the original solution of the glycine-modified boron nitride nanosheet dispersion to increase the concentration of functionalized boron nitride in the glycine-modified boron nitride nanosheet dispersion, which is beneficial to subsequent modification.

[0041] After obtaining the first mixed dispersion, the first mixed dispersion, FeCl3·6H2O, FeCl2·4H2O, NaOH solution and ethanol are mixed for coating modification treatment to obtain the magnetically modified boron nitride nanosheets.

[0042] As an embodiment of the present invention, the coating modification treatment may include: second mixing the first mixed dispersion, FeCl3·6H2O and FeCl2·4H2O to obtain a second mixed dispersion; adjusting the pH value of the second mixed dispersion to 10 with NaOH solution, and then third mixing the obtained system with ethanol. As an embodiment of the present invention, the second mixing is carried out under stirring conditions, the rotation speed of the second mixing is 700 rpm, and the time is 1-2 h, specifically 1.5 h. As an embodiment of the present invention, the mass ratio of FeCl3·6H2O to FeCl2·4H2O is 1.167-4.668:0.429-1.717. As an embodiment of the present invention, the concentration of the NaOH solution is 1 mol / L; the volume of the ethanol is 5-20 mL. The present invention adds NaOH solution to adjust the pH value of the second mixed dispersion to 10, providing conditions for the formation of magnetite. Under the condition of pH 10, Fe 2+ and Fe 3+The hydroxides are simultaneously completely co-precipitated to form magnetite; ethanol is added in the present invention to prevent the aggregation of magnetite particles. As an embodiment of the present invention, the time of the third mixing can be 3 to 10 min, specifically 5 min.

[0043] As an embodiment of the present invention, after the coating modification treatment, it is preferably further included: centrifuging the product system obtained after the coating modification treatment, and sequentially washing and drying the obtained solid product to obtain magnetically modified boron nitride nanosheets. The rotation speed of the centrifugation can be 2000 rpm, and the time can be 10 min. In the examples of the present invention, specifically, the solid product obtained after centrifugation is sequentially centrifuged and washed 3 times with water and ethanol respectively, the precipitate after centrifugation and washing is dispersed in water and ultrasonicated for 30 min, and the obtained precipitate dispersion is vacuum filtered through a filter membrane with a pore size of 0.22 μm to remove free Fe3O4 nanoparticles, and then the obtained filter cake is washed with water until the filtrate is neutral. The present invention has no special limitation on the drying.

[0044] The present invention adopts a method of ball milling-assisted liquid-phase ultrasonic exfoliation, uses glycine as a modifier, and grafts glycine molecules at the edges and defects of boron nitride through covalent modification to obtain glycine-modified boron nitride. Hydroxyl and amino groups derived from glycine molecules are grafted at the edges and defects of boron nitride through covalent modification to obtain glycine-modified boron nitride nanosheets, and magnetite is coated on the glycine-modified boron nitride nanosheets through electrostatic interaction to obtain magnetically modified boron nitride nanosheets.

[0045] The present invention provides a method for preparing the modified boron nitride-epoxy resin composite material described in the above technical solution, including the following steps:

[0046] Mix epoxy resin, heat-conducting filler and curing agent to obtain a mixed dispersion;

[0047] Form the mixed dispersion under the condition of an external magnetic field to obtain a formed body;

[0048] Cure the formed body to obtain the modified boron nitride-epoxy resin composite material.

[0049] The present invention mixes epoxy resin, heat-conducting filler and curing agent to obtain a mixed dispersion. As an embodiment of the present invention, the mass ratio of the epoxy resin, heat-conducting filler and curing agent can be 45 to 60:20 to 50:15 to 20, and further can be 50 to 60:35 to 50:16 to 20.

[0050] As an embodiment of the present invention, the mixing can include: performing a first mixing on the epoxy resin and the heat-conducting filler to obtain a first mixture; performing a second mixing on the first mixture and the curing agent to obtain a mixed dispersion.

[0051] As an embodiment of the present invention, before the first mixing, it is preferable to preheat the epoxy resin. The preheating temperature is 60°C and the time is 15 min. After preheating, the viscosity of the epoxy resin decreases, and the subsequent addition of fillers is more uniformly dispersed.

[0052] As an embodiment of the present invention, the first mixing can be carried out by ultrasonic treatment and heating stirring in sequence. The time of ultrasonic treatment can be 10 - 20 min, specifically 15 min. The temperature of heating stirring can be 60°C, and the rotation speed can be 450 - 500 rpm. The time can be 1 - 2 h, specifically 1.5 h. As an embodiment of the present invention, the second mixing can be adding the curing agent to the first mixture. The temperature of the second mixing can be 20 - 30°C, specifically 25°C, and the rotation speed can be 600 - 650 rpm. The time can be 5 min.

[0053] In the present invention, the heat-conducting filler is first mixed with the epoxy resin, which can ensure the uniform dispersion of the heat-conducting filler in the epoxy resin, avoid the aggregation of the heat-conducting filler due to non-dispersion, and cause a decrease in heat-conducting performance. Then, it is mixed with the curing agent, which can better control the speed and temperature of the curing reaction, which helps to ensure the stability of the curing process and the quality of the product.

[0054] After obtaining the mixed dispersion liquid in the present invention, the mixed dispersion liquid is formed under the condition of the presence of an external magnetic field to obtain a formed body.

[0055] As an embodiment of the present invention, preferably before forming, it further includes: performing vacuum degassing on the mixed dispersion liquid. The vacuum degree of the vacuum degassing can be 0.1 MPa, and the time of the vacuum degassing can be 15 - 30 min, specifically 20 min. The present invention preferably performs vacuum degassing in a vacuum degassing machine.

[0056] Performing vacuum degassing on the mixed dispersion liquid in the present invention can remove the bubbles in the mixed dispersion liquid, improve the uniform dispersion of the fillers in the mixed dispersion liquid, is beneficial to heat transfer, and improves the heat-conducting performance.

[0057] As an embodiment of the present invention, the forming is casting forming. The intensity of the external magnetic field can be 200 - 800 GS, specifically 600 GS. During the casting forming process, the direction of the external magnetic field is perpendicular to the direction of the casting tape used for casting forming. The height of the doctor blade used for casting forming can be 0.2 - 2 mm.

[0058] The present invention forms a film-like modified boron nitride-epoxy resin composite material by casting forming. The relatively thin modified boron nitride-epoxy resin composite material prepared by casting forming is beneficial to improving the heat transfer efficiency. In the process of casting forming, a magnetic field in the vertical direction is introduced in the present invention, so that glycine-modified boron nitride is arranged parallel to the casting belt under the action of the mechanical force of the casting knife, and the magnetic modified boron nitride nanosheets are arranged along the direction perpendicular to the casting belt under the action of the magnetic field, obtaining a three-dimensional network of modified boron nitride with oriented arrangement in both the vertical and parallel directions of the casting belt, constructing an effective heat conduction path, and further realizing the high thermal conductivity of the modified boron nitride-epoxy resin composite material.

[0059] After the formed body is obtained in the present invention, the formed body is cured to obtain the modified boron nitride-epoxy resin composite material.

[0060] As an embodiment of the present invention, the curing includes first curing and second curing in sequence; the temperature of the first curing can be 50-60°C, and the time can be 3-5 h; the temperature of the second curing can be 20-30°C, and the time can be 8-10 h.

[0061] In the present invention, the two-stage curing can improve the mechanical properties and thermal conductivity of the composite material, and can also improve the heat resistance and stability of the composite material. The first curing can quickly form and fix the orientation arrangement of the fillers inside the resin; the second curing can further stabilize the material properties and ensure the long-term use effect. The temperature of the first curing is 50-60°C, which can improve the bonding performance and thermal conductivity of the thermal conductive composite material, and can also shorten the time of the first curing. The temperature of the second curing is 20-30°C, curing at room temperature, prolonging the curing time, ensuring the stability of the material, and reducing the internal stress of the material.

[0062] The present invention provides the application of the modified boron nitride-epoxy resin composite material described in the above technical solution or the modified boron nitride-epoxy resin composite material prepared by the described preparation method as a thermal interface material in electronic devices.

[0063] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0064] Example 1

[0065] This example prepares a 3D Gly-BN / Fe3O4@BNNS / EP composite material according to the following steps:

[0066] Step 1: Prepare Gly-BN

[0067] Weigh 10 g of h-BN, 30 g of glycine and 120 g of deionized water and put them into a ball milling jar. Ball mill for 12 h at a rotation speed of 400 rpm. Use deionized water to carry out suction filtration and washing on the ball milled product, and collect the suction filtered solid; Mix isopropanol and deionized water in a volume ratio of 1:1 to obtain an ultrasonic aid. Disperse the solid in the ultrasonic aid to obtain a dispersion with a concentration of 10 mg / mL. Ultrasonic the dispersion for 6 h and let it stand for 12 h at 25 °C. After standing and separation, the supernatant and the precipitate are obtained respectively. The supernatant is a functionalized boron nitride nanosheet dispersion. Dry the precipitate to obtain Gly-BN with an average thickness of 240 nm and an average in-plane size of 8.9 μm.

[0068] Step 2: Prepare Fe3O4@BNNS

[0069] Take 2000 mL of the functionalized boron nitride nanosheet dispersion obtained in Step 1 and heat it to evaporate to 200 mL at 200 °C, then ultrasonic disperse for 10 min. Add 1 g of polyvinylpyrrolidone and stir magnetically at a rotation speed of 600 rpm for 1 h; Add 4.668 g of FeCl3·6H2O and 1.717 g of FeCl2·4H2O to the obtained mixed dispersion, stir magnetically at a rotation speed of 700 rpm for 1.5 h, and then adjust the pH value of the reaction system to 10 with 1 mol / L NaOH solution. Add 5 mL of ethanol and stir for 5 min, centrifuge at a rotation speed of 2000 rpm for 10 min, separate to obtain a precipitate, wash the precipitate with deionized water and ethanol by centrifugation for 3 times. Take the washed precipitate and disperse it in 50 mL of deionized water and ultrasonic for 30 min. Vacuum filter the obtained precipitate dispersion with a filter membrane with a pore size of 0.22 μm to remove free Fe3O4 nanoparticles. Wash the obtained filter cake with deionized water until the filtrate is neutral. Dry the washed filter cake at 60 °C for 8 h to obtain Fe3O4@BNNS with an average thickness of 2.3 nm and an average in-plane size of 1.8 μm.

[0070] Step 3: Prepare 3D Gly-BN / Fe3O4@BNNS / EP composite

[0071] Preheat 5.6 g of bisphenol F resin (epoxy equivalent 170) at 60 °C for 15 min. Add 1.6 g of Gly-BN obtained in step 1 and 3.2 g of Fe3O4@BNNS obtained in step 2 to the bisphenol F resin, ultrasonicate for 15 min, stir at 60 °C and 450 rpm for 1.5 h, add 1.867 g of curing agent 5010B, magnetically stir at a speed of 600 rpm for 5 min, vacuum degas the obtained mixed dispersion under a vacuum degree of 0.1 MPa for 20 min, cast and form the obtained mixed slurry under the action of a magnetic field, the magnetic field strength is 600 GS, the direction of the applied magnetic field is perpendicular to the direction of the casting tape used for casting and forming, and the height of the doctor blade used for casting and forming is 0.2 mm; then cure at 60 °C for 3 h and cure at room temperature for 8 h in sequence to obtain a 3D Gly-BN / Fe3O4@BNNS / EP composite material, and the sample is marked as GFE1.

[0072] Perform thermal conductivity detection on GFE1. The measured in-plane thermal conductivity is 4.858 W / (m·K), and the through-plane thermal conductivity is 1.841 W / (m·K).

[0073] Example 2

[0074] Prepare the 3D Gly-BN / Fe3O4@BNNS / EP composite material according to the following steps in this example:

[0075] Step 1: The preparation method is the same as that in step 1 of Example 1 to obtain Gly-BN with an average thickness of 240 nm and an average in-plane size of 8.9 μm.

[0076] Step 2: It is basically the same as the preparation method in step 2 of Example 1, except that the mass of FeCl3·6H2O added is 2.334 g and the mass of FeCl2·4H2O added is 0.858 g to obtain Fe3O4@BNNS with an average thickness of 2.3 nm and an average in-plane size of 1.8 μm.

[0077] Step 3: It is basically the same as the preparation method in step 3 of Example 1, except that the mass of Fe3O4@BNNS obtained in step 2 added is 2.4 g. Finally, a 3D Gly-BN / Fe3O4@BNNS / EP composite material is obtained, and the sample is marked as GFE2.

[0078] Perform thermal conductivity detection on GFE2. The measured in-plane thermal conductivity is 4.278 W / (m·K), and the through-plane thermal conductivity is 1.184 W / (m·K).

[0079] Example 3

[0080] The 3D Gly-BN / Fe3O4@BNNS / EP composite material was prepared in the following steps in this example:

[0081] Step 1: The same preparation method as in Step 1 of Example 1 was used to obtain Gly-BN with an average thickness of 240 nm and an average in-plane size of 8.9 μm.

[0082] Step 2: The preparation method was basically the same as in Step 2 of Example 1, except that the mass of FeCl3·6H2O added was 1.167 g and the mass of FeCl2·4H2O added was 0.429 g, and Fe3O4@BNNS with an average thickness of 2.3 nm and an average in-plane size of 1.8 μm was obtained.

[0083] Step 3: The preparation method was basically the same as in Step 3 of Example 1, except that the mass of Fe3O4@BNNS obtained in Step 2 added was 2.0 g. The 3D Gly-BN / Fe3O4@BNNS / EP composite material was finally obtained, and the sample was labeled GFE3.

[0084] The thermal conductivity of GFE3 was detected, and the in-plane thermal conductivity measured was 5.606 W / (m·K), and the cross-plane thermal conductivity was 0.982 W / (m·K).

[0085] Comparative Example 1

[0086] The epoxy resin matrix was prepared in the following steps in this comparative example:

[0087] 5.6 g of bisphenol F resin (epoxy equivalent 170) was preheated at 60 °C for 15 min, 1.867 g of curing agent 5010B was added, and it was magnetically stirred at a speed of 600 rpm for 5 min. The obtained mixed dispersion was vacuum degassed for 20 min, and the obtained mixed slurry was cast into a film. Then it was cured at 60 °C for 3 h and cured at room temperature for 8 h to obtain the epoxy resin matrix.

[0088] The thermal conductivity of the epoxy resin matrix was detected, and the in-plane thermal conductivity measured was 0.185 W / (m·K).

[0089] Comparative Example 2

[0090] The BN / EP composite material was prepared in the following steps in this comparative example:

[0091] Preheat 5.6 g of bisphenol F resin (epoxy equivalent 170) at 60 °C for 15 min, add 3.2 g of unpeeled modified h-BN to the bisphenol F resin, sonicate for 15 min, stir at 60 °C and 450 rpm for 1.5 h, add 1.867 g of curing agent 5010B, magnetically stir at a speed of 600 rpm for 5 min, vacuum degas the obtained mixed dispersion for 20 min, cast the obtained mixed slurry into a film, and then cure it at 60 °C for 3 h and at room temperature for 8 h to obtain the BN / EP composite material, and the sample is labeled as BE.

[0092] Conduct thermal conductivity detection on BE, and the measured in-plane thermal conductivity is 2.723 W / (m·K).

[0093] According to Examples 1 to 3 and Comparative Examples 1 to 2, in Comparative Example 1, only the epoxy resin matrix is used as the thermal conductive material, and its in-plane thermal conductivity is 0.185 W / (m·K); in Comparative Example 2, unmodified h-BN is used as the filler and a three-dimensional thermal conductive network is not constructed, and its in-plane thermal conductivity is 2.723 W / (m·K); the inter-plane thermal conductivity of the modified boron nitride-epoxy resin composite materials prepared in Examples 1 to 3 is 0.982 - 1.841 W / (m·K), and the in-plane thermal conductivity is 4.278 - 5.606 W / (m·K), which are all higher than the thermal conductivities of Comparative Examples 1 to 2. In the present invention, glycine-modified boron nitride and magnetically modified boron nitride nanosheets are used as thermal conductive fillers and dispersed in the epoxy resin matrix, so that there is an oriented arrangement of the modified boron nitride three-dimensional network in both the vertical and parallel directions of the casting tape, improving the thermal conductivity of the modified boron nitride-epoxy resin composite material, which is beneficial to the application of the modified boron nitride-epoxy resin composite material in the field of electronic devices.

[0094] Figure 1 It is a schematic diagram of preparing a modified boron nitride-epoxy resin composite material by magnetic field-assisted casting. According to Figure 1 It can be seen that in the casting process of the present invention, a magnetic field in the vertical direction is introduced, so that glycine-modified boron nitride is arranged parallel to the casting tape under the action of the mechanical force of the casting blade, and the magnetically modified boron nitride nanosheets are arranged perpendicular to the casting tape direction under the action of the magnetic field, obtaining a three-dimensional network of modified boron nitride with oriented arrangement in both the vertical and parallel directions of the casting tape, constructing an effective heat conduction path, and thus realizing the high thermal conductivity of the modified boron nitride-epoxy resin composite material.

[0095] Figure 2 It is a scanning electron micrograph of the modified boron nitride-epoxy resin composite material in Example 1. According to Figure 2 It can be seen that the modified boron nitride-epoxy resin composite material prepared in this application has a double-oriented BN network structure with vertical and horizontal arrangements.

[0096] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A modified boron nitride-epoxy resin composite material, comprising an epoxy resin matrix and a thermally conductive filler dispersed in the epoxy resin matrix; the thermally conductive filler comprises glycine-modified boron nitride and magnetically modified boron nitride nanosheets, and the magnetically modified boron nitride nanosheets are glycine-modified boron nitride nanosheets coated with ferrosoferric oxide particles.

2. The modified boron nitride-epoxy resin composite material according to claim 1, characterized in that: The mass of the thermal conductive filler is 10-40% of the mass of the modified boron nitride-epoxy resin composite material; the mass ratio of the glycine-modified boron nitride to the magnetic-modified boron nitride nanosheets is 1-2:1-3.

3. The modified boron nitride-epoxy resin composite material according to claim 2, characterized in that: The thickness of the glycine-modified boron nitride is 100-300 nm, and the in-plane size is 5-10 μm; the thickness of the magnetically modified boron nitride nanosheet is 1-5 nm, and the in-plane size is 300-5000 nm, and the particle size of the ferrosoferric oxide particles on the magnetically modified boron nitride nanosheet is 50-2000 nm.

4. The modified boron nitride-epoxy resin composite material according to claim 1, characterized in that: The epoxy resin matrix is ​​formed by curing the epoxy resin in the presence of a curing agent; the epoxy resin includes a bisphenol F type resin; the curing agent includes an amine curing agent; the mass ratio of the epoxy resin to the curing agent is 9 to 16:

4.

5. The method for preparing the modified boron nitride-epoxy resin composite material according to any one of claims 1 to 4, comprising the following steps: mixing epoxy resin, thermal conductive filler and curing agent to obtain a mixed dispersion; Molding the mixed dispersion in the presence of an external magnetic field to obtain a molded body; The molded body is cured to obtain the modified boron nitride-epoxy resin composite material.

6. The preparation method according to claim 5, characterized in that: The intensity of the external magnetic field is 200-800 GS, and the molding includes tape casting.

7. The preparation method according to claim 6, characterized in that: During the tape casting process, the direction of the external magnetic field is perpendicular to the direction of the casting belt used for the tape casting.

8. The preparation method according to claim 5, characterized in that: The curing comprises a first curing and a second curing performed sequentially; the first curing is performed at a temperature of 50 to 60° C. for 3 to 5 hours; the second curing is performed at a temperature of 20 to 30° C. for 8 to 10 hours.

9. The preparation method according to claim 5, characterized in that: The mixing includes: first mixing the epoxy resin and the thermal conductive filler to obtain a first mixed material; and second mixing the first mixed material and the curing agent to obtain a mixed dispersion.

10. Use of the modified boron nitride-epoxy resin composite material according to any one of claims 1 to 4 or the modified boron nitride-epoxy resin composite material prepared by the preparation method according to any one of claims 5 to 9 as a thermal interface material in electronic equipment.

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