A heat-conducting electromagnetic shielding silicone rubber composite film, a preparation method and application thereof

Abstract

The application discloses a heat-conducting electromagnetic shielding silicone rubber composite film and a preparation method and application thereof. The heat-conducting electromagnetic shielding silicone rubber composite film comprises a carbon-fiber-containing silicone rubber layer, a metal powder layer and a carbon-fiber-containing silicone rubber layer which are sequentially stacked, and the composition of the metal powder layer comprises flaky metal powder loaded with carbon material. The preparation method of the heat-conducting electromagnetic shielding silicone rubber composite film comprises the following steps: 1) preparing a carbon-fiber-containing silicone rubber raw material mixture; 2) preparing a carbon-fiber-containing silicone rubber layer; 3) preparing a metal powder layer on the surface of the carbon-fiber-containing silicone rubber layer; and 4) preparing a carbon-fiber-containing silicone rubber on the surface of the metal powder layer. The heat-conducting electromagnetic shielding silicone rubber composite film has the advantages of excellent heat-conducting performance, outstanding electromagnetic shielding performance, good mechanical properties and thin thickness, and has a simple preparation process, low production cost and wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic silicone rubber, in particular to a kind of heat-conducting electromagnetic shielding silicone rubber composite film and its preparation method and application. BACKGROUND

[0002] With the rapid development of electronic communication technology, the integration and high power of electronic components lead to a sharp increase in heat generation, which directly affects the operation stability and safety of communication equipment, so higher requirements are put forward for the heat dissipation of communication equipment and electronic components. At the same time, various electromagnetic radiation in the environment not only interferes with the normal operation of communication equipment, but also may pose a potential threat to human health.

[0003] However, the heat conduction performance and electromagnetic shielding performance of existing electronic materials are often difficult to balance, and cannot meet the application scene requirements of miniaturization and integration of electronic components. For example: CN 116669412 A discloses a heterogeneous structure heat-conducting electromagnetic shielding silicone rubber, which is prepared by blending heat-conducting and electromagnetic shielding silicone filler, vinyl silicone oil, hydrogen-containing silicone oil, platinum catalyst and inhibitor uniformly, then vulcanizing to form a heat-conducting and electromagnetic shielding silicone layer, and then placing the heat-conducting and electromagnetic shielding silicone layer in a dispersion liquid prepared from heat-conducting and insulating filler, vinyl silicone oil, hydrogen-containing silicone oil, platinum catalyst, inhibitor and solvent to perform stirring swelling, heating curing and reduced pressure distillation to finally obtain the heterogeneous structure heat-conducting electromagnetic shielding silicone rubber. The electromagnetic shielding efficiency of the heat-conducting electromagnetic shielding silicone rubber reaches 63.3dB-71.1dB, but the thermal conductivity is only 2.3W·m -1 ·K -1 , which is not suitable for application in occasions with high heat conduction performance requirements.

[0004] Therefore, it is of great significance to develop a silicone rubber material with excellent heat conduction performance and excellent electromagnetic shielding performance. SUMMARY

[0005] The purpose of the present application is to provide a kind of heat-conducting electromagnetic shielding silicone rubber composite film and its preparation method and application.

[0006] The technical scheme adopted by the present application is:

[0007] A kind of heat-conducting electromagnetic shielding silicone rubber composite film, which includes carbon fiber-containing silicone rubber layer, metal powder layer and carbon fiber-containing silicone rubber layer arranged in sequence; the composition of the metal powder layer includes flaky metal powder loaded with carbon material on the surface.

[0008] Preferably, the length of the carbon fiber is 50μm-300μm.

[0009] Preferably, the carbon material in the flaky metal powder loaded with carbon material is at least one of carbon nanotube powder, graphite powder, graphene powder, and the particle size of the carbon material is 1 nm to 5 μm.

[0010] Preferably, the flaky metal powder in the flaky metal powder loaded with carbon material is at least one of flaky copper powder, flaky nickel powder, and flaky silver powder, and the flake size of the flaky metal powder is 1 μm to 30 μm.

[0011] Preferably, the mass percentage of the carbon material in the flaky metal powder loaded with carbon material is 3% to 15%.

[0012] Preferably, the flaky metal powder loaded with carbon material is prepared by a preparation method comprising the following steps: mixing flaky metal powder, carbon material, mercapto silane coupling agent, and solvent to perform plasma ball milling, and then drying to obtain the flaky metal powder loaded with carbon material.

[0013] Preferably, the mass ratio of the flaky metal powder, carbon material, mercapto silane coupling agent, and solvent is 10 to 30: 1 to 5: 0.10 to 1.25: 0.1 to 0.6.

[0014] Preferably, the mercapto silane coupling agent is at least one of γ-mercaptopropyl trimethoxysilane, γ-mercaptopropyl methyl dimethoxysilane, and 3-mercaptopropyl triethoxysilane.

[0015] Preferably, the solvent is at least one of ethanol, water, and isopropyl alcohol.

[0016] Preferably, the plasma ball milling is performed under the conditions of a plasma discharge frequency of 6 kHz to 12 kHz, a pressure of 0.05 MPa to 0.25 MPa, and a ball mill rotation speed of 600 rpm to 2000 rpm, and the ball milling is intermittent ball milling, each ball milling is performed for 10 min to 20 min, and each ball milling is paused for 20 min to 40 min, and the total ball milling operation time is 2 h to 5 h.

[0017] Preferably, the plasma ball milling is performed under the conditions of a mass ratio of zirconia balls to materials of 10 to 100: 1 and a total volume of the balls and materials accounting for 20% to 60% of the volume of the ball mill tank.

[0018] Preferably, the plasma ball milling is performed in argon, nitrogen, or air.

[0019] Preferably, the drying is performed under the condition of a temperature of 80°C to 120°C, and the drying time is 1 h to 6 h.

[0020] Preferably, the thickness of the carbon fiber-containing silicone rubber layer is 50 μm to 200 μm.

[0021] Preferably, the thickness of the metal powder layer is 10 μm to 100 μm.

[0022] Preferably, the heat-conductive electromagnetic shielding silicone rubber composite film comprises the following components by mass:

[0023] vinyl silicone oil: 100 parts;

[0024] hydrogen-containing silicone oil: 1 part to 10 parts;

[0025] carbon fiber: 10 parts to 200 parts;

[0026] sheet-shaped metal powder with surface-loaded carbon material: 5 parts to 80 parts;

[0027] platinum catalyst: 0.1 part to 0.5 part;

[0028] inhibitor: 0.001 part to 0.02 part.

[0029] Preferably, the viscosity of the vinyl silicone oil is 90 mPa·s to 2000 mPa·s.

[0030] Preferably, the hydrogen content of the hydrogen-containing silicone oil is 0.1% to 1.0%.

[0031] Preferably, the platinum catalyst is at least one of methylvinylsiloxane-platinum complex, isopropanol solution of chloroplatinic acid, platinum-tetrahydrofuran complex, vinyl polysiloxane-platinum complex.

[0032] Preferably, the inhibitor is at least one of ethynylcyclohexanol, 3,5-dimethyl-1-hexyn-3-ol, 3,6-dimethyl-1-heptyne-3-ol.

[0033] A method for preparing the heat-conductive electromagnetic shielding silicone rubber composite film as described above comprises the following steps:

[0034] 1) mixing the vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, platinum catalyst and inhibitor uniformly, and then defoaming to obtain a silicone rubber raw material mixture;

[0035] 2) pressing the silicone rubber raw material mixture into a sheet shape and then vulcanizing to form a silicone rubber layer containing carbon fiber;

[0036] 3) dispersing the sheet-shaped metal powder with surface-loaded carbon material with a solvent, and then coating on the surface of the silicone rubber layer containing carbon fiber and drying to form a metal powder layer;

[0037] 4) coating the silicone rubber raw material mixture on the surface of the metal powder layer and pressing into a sheet shape, and then vulcanizing to obtain the heat-conductive electromagnetic shielding silicone rubber composite film.

[0038] Preferably, the defoaming manner of step 1) is vacuum defoaming.

[0039] Preferably, the vacuum defoaming is performed under a vacuum degree of 133 Pa to 1000 Pa, and the time for vacuum defoaming is 10 min to 30 min.

[0040] Preferably, the vulcanization of step 2) is performed at a temperature of 100 DEG C to 180 DEG C, and the time for vulcanization is 2 min to 60 min.

[0041] Preferably, the solvent of step 3) is at least one of ethanol, water and isopropyl alcohol.

[0042] Preferably, the coating manner of step 3) is spraying.

[0043] Preferably, the vulcanization of step 4) is performed at a temperature of 100 DEG C to 180 DEG C, and the time for vulcanization is 2 min to 60 min.

[0044] An electronic device comprising the heat-conductive electromagnetic shielding silicone rubber composite film.

[0045] The principle of the present application is that the carbon material is loaded on the flaky metal powder by plasma ball milling, the high temperature generated by plasma excitation causes local melting of the surface of the flaky metal powder, the carbon material is embedded in the surface layer of the flaky metal powder, and a firm interface bonding is formed between the two, providing more heterogeneous interfaces and improving the electrical conductivity and thermal conductivity of the composite powder; the coordination bonding is formed between the mercapto group of the mercapto silane coupling agent and the metal on the flaky metal powder, the mercapto silane coupling agent can be connected to the surface of the flaky metal powder, which is beneficial to enhancing the interface bonding between the supported metal powder and the silicone rubber during spraying; the carbon fiber can be in-plane oriented in the silicone rubber matrix by calendering, and a perfect in-plane thermal conduction path is constructed in the surface layer of the film, and the middle metal powder layer can form a vertical thermal conduction path with the silicone rubber layer containing the carbon fiber, so that a complete three-dimensional thermal conduction path can be constructed; the upper, middle and lower three layers of the composite film have good electrical conductivity, and the electromagnetic wave can be subjected to multiple reflection loss between the adjacent two layers, in addition, the flaky metal powder loaded with carbon material can provide a large number of heterogeneous interfaces, increase the interface polarization loss, so that the electromagnetic wave can be strongly absorbed and reflected, and finally excellent electromagnetic shielding performance is exhibited.

[0046] The heat-conductive electromagnetic shielding silicone rubber composite film of the present application has excellent heat conduction performance, outstanding electromagnetic shielding performance, good mechanical properties, thin thickness and the like, and its preparation process is simple, the production cost is low, and it has a wide application prospect in the fields of 5G communication, consumer electronics, power battery, national defense and military industry, etc.

[0047] Specifically:

[0048] 1) The heat-conducting electromagnetic shielding silicone rubber composite film of the present application has a sandwich structure, and the carbon fibers in the carbon fiber-containing silicone rubber layers on the upper and lower surfaces can build a perfect in-plane heat-conducting network in the composite film, while the flaky metal powder loaded with carbon materials in the metal powder layer can be connected with the carbon fibers in the carbon fiber-containing silicone rubber layers on the upper and lower layers to form a vertical heat-conducting path, thereby building a perfect three-dimensional heat-conducting path in the composite film, which can significantly improve the heat-conducting performance of the composite film;

[0049] 2) The three-layer structure of the heat-conducting electromagnetic shielding silicone rubber composite film of the present application has high electrical conductivity, can reflect a large amount of electromagnetic waves, and the electromagnetic waves will undergo multiple reflections between the adjacent two layers, which is conducive to the efficient absorption of electromagnetic waves, and can significantly improve the electromagnetic shielding performance of the composite film;

[0050] 3) The heat-conducting electromagnetic shielding silicone rubber composite film of the present application has a heat-conducting coefficient and electromagnetic shielding effectiveness that increases with the increase of the content of carbon fibers and flaky metal powder loaded with carbon materials, thereby meeting the application requirements of different scenarios;

[0051] 4) The heat-conducting electromagnetic shielding silicone rubber composite film of the present application has good heat-conducting performance (the in-plane heat-conducting coefficient can be as high as 17.13 W·m -1 ·K -1 ), excellent electromagnetic shielding performance (the electromagnetic shielding effectiveness EMI SE can be as high as 67.85 dB), and good stability of electromagnetic shielding performance under external force (after 1500 times of 180° repeated bending, the EMI SE can still reach 66.65 dB), which can be widely applied in the fields of 5G communication, consumer electronics, power batteries, national defense and military industry, etc. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a structure schematic diagram of the heat-conducting electromagnetic shielding silicone rubber composite film of the present application.

[0053] The figure mark explanation: 10, carbon fiber-containing silicone rubber layer; 20, metal powder layer; 30, carbon fiber-containing silicone rubber layer.

[0054] Figure 2 It is a SEM diagram of the cross section of the heat-conducting electromagnetic shielding silicone rubber composite film of Example 6.

[0055] Figure 3 It is a graph of the electromagnetic shielding effectiveness test results of the heat-conducting electromagnetic shielding silicone rubber composite films of Examples 1-6 and the silicone rubber composite films of Comparative Examples 1-3 in the X-band.

[0056] Figure 4The results of the thermal conductivity test of the heat-conductive electromagnetic shielding silicone rubber composite film of Examples 1 to 6 and the silicone rubber composite film of Comparative Examples 1 to 3 are shown in the following graph.

[0057] Figure 5 The results of the electromagnetic shielding efficiency test of the heat-conductive electromagnetic shielding silicone rubber composite film of Example 6 before and after 1500 times of 180° bending in the X-band are shown in the following graph. DETAILED DESCRIPTION

[0058] The present application will be further explained and described with reference to the following specific examples.

[0059] Example 1

[0060] A heat-conductive electromagnetic shielding silicone rubber composite film (structure diagram as shown in Figure 1 The raw material composition of the heat-conductive electromagnetic shielding silicone rubber composite film is shown in the following table.

[0061] Table 1 Raw material composition table of a heat-conductive electromagnetic shielding silicone rubber composite film

[0062] Raw materials Amount (mass parts) Vinyl silicone oil (viscosity: 180 mPa-s) 100 Hydrogen-containing silicone oil (hydrogen content: 0.18%) 1 Carbon fiber (average length: 250 μm) 80 Carbon nanotube-loaded flaky copper powder 10 Methylvinylsiloxane-platinum complex 0.2 Ethynylcyclohexanol 0.02

[0063] Note:

[0064] The carbon nanotube-loaded flaky copper powder is prepared by the following method:

[0065] 50 parts by mass of flaky copper powder (flake diameter of 20 μm), 3 parts by mass of carbon nanotube powder (tube diameter of 10 nm, length of 5 μm), and 0.5 parts by mass of 3-mercaptopropyl triethoxysilane are added into a ball mill tank, 2 parts by mass of anhydrous ethanol is added, zirconium oxide balls are added according to a ball-to-charge mass ratio of 60:1, the ball mill tank is sealed and installed on a plasma-assisted ball mill, a vacuum pump is started, vacuum is pumped to negative pressure, the gas pressure in the ball mill tank is maintained at 0.05 MPa, the vacuum valve is closed, the running delay is set to 20 min, the machine is stopped for 20 min, the working frequency is 6 times, the total ball milling working time is 2 h, the vibration control power supply and the discharge control power supply are started in turn, then the ball mill is started, the ball mill speed is adjusted to 1200 rpm, the discharge frequency is 10 kHz, the mixed powder is separated, and vacuum drying is performed at 80°C for 1 h, thereby obtaining the carbon nanotube-loaded flaky copper powder (the content of carbon nanotube is 5.6 wt%).

[0066] The preparation method of the heat-conductive electromagnetic shielding silicone rubber composite film is as follows:

[0067] 1) The vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl silicone-palladium complex, and ethynyl cyclohexanol are added into a homogenizer, the rotation speed of the homogenizer is adjusted to 2000 rpm, and mixing is performed for 40 s, then the mixture is placed in a vacuum box, the vacuum degree is set to 133 Pa, and vacuum is pumped for 20 min, thereby obtaining a silicone rubber raw material mixture;

[0068] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release films, place between the two rollers of a calender, and calendered at a speed of 0.2 m / min to form a sheet, then place the sheet in an oven and vulcanize at 120°C for 2 min, then remove the upper and lower release films to form a carbon fiber-containing silicone rubber layer (150 μm thick);

[0069] 3) Disperse the carbon nanotube-loaded flaky copper powder in ethanol, and spray the dispersion uniformly on the surface of the carbon fiber-containing silicone rubber layer at a spraying speed of 10 mL / min for 30 s, then place in an oven and heat at 70°C for 10 min to form a metal powder layer (30 μm thick);

[0070] 4) Apply the silicone rubber raw material mixture to the surface of the metal powder layer, cover the upper and lower surfaces with polyester release films, place between the two rollers of a calender, and calendered at a speed of 0.2 m / min to form a sheet, then place the sheet in an oven and vulcanize at 125°C for 5 min to form a carbon fiber-containing silicone rubber layer (150 μm thick), then remove the upper and lower release films to obtain the heat-conductive electromagnetic shielding silicone rubber composite film (330 μm thick).

[0071] Example 2:

[0072] A heat-conductive electromagnetic shielding silicone rubber composite film (structure schematic as shown in Figure 1 The raw material composition is shown in the following table:

[0073] Table 2 Raw material composition table of a heat-conductive electromagnetic shielding silicone rubber composite film

[0074]

[0075] The preparation method of the above heat-conductive electromagnetic shielding silicone rubber composite film is as follows:

[0076] 1) Add vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methylvinylsiloxane-platinum complex, and ethynylcyclohexanol into a homogenizer, adjust the rotation speed of the homogenizer to 2000 rpm, and mix for 40 s, then place in a vacuum tank and set the vacuum degree to 133 Pa, and vacuumize for 20 min to obtain a silicone rubber raw material mixture;

[0077] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release films, place between the two rollers of a calender, and calendered at a speed of 0.2 m / min to form a sheet, then place the sheet in an oven and vulcanize at 120°C for 2 min, then remove the upper and lower release films to form a carbon fiber-containing silicone rubber layer (150 μm thick);

[0078] 3) The carbon nanotube-loaded flaky copper powder is dispersed in ethanol, the ratio of the carbon nanotube-loaded flaky copper powder to ethanol is 1 g:3 mL, and then the mixture is uniformly sprayed on the surface of the carbon fiber-containing silicone rubber layer at a spraying speed of 10 mL / min, the spraying time is 40 s, and then the mixture is placed in an oven and heated at 70°C for 10 min to form a metal powder layer (40 μm thick);

[0079] 4) The silicone rubber raw material mixture is coated on the surface of the metal powder layer, and then the upper and lower surfaces are covered with polyester release films, and then the mixture is placed between the two rollers of a calendering machine to make a sheet at a calendering speed of 0.2 m / min, and then the sheet is placed in an oven and vulcanized at 125°C for 5 min to form a carbon fiber-containing silicone rubber layer (150 μm thick), and then the upper and lower release films are removed to obtain the heat-conductive electromagnetic shielding silicone rubber composite film (340 μm thick).

[0080] Example 3:

[0081] A heat-conductive electromagnetic shielding silicone rubber composite film (structure schematic diagram as shown in Figure 1 The raw material composition of the heat-conductive electromagnetic shielding silicone rubber composite film is shown in the following table:

[0082] Table 3 Raw material composition table of a heat-conductive electromagnetic shielding silicone rubber composite film

[0083]

[0084] The preparation method of the heat-conductive electromagnetic shielding silicone rubber composite film is as follows:

[0085] 1) The vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl silicone-palladium complex, and 3,6-dimethyl-1-heptyne-3-ol are added to a homogenizer, the rotation speed of the homogenizer is adjusted to 2000 rpm, and the mixture is mixed for 40 s, and then the mixture is placed in a vacuum box, the vacuum degree is set to 133 Pa, and the vacuum is pumped for 20 min to obtain a silicone rubber raw material mixture;

[0086] 2) The upper and lower surfaces of the silicone rubber raw material mixture are covered with polyester release films, and then the mixture is placed between the two rollers of a calendering machine to make a sheet at a calendering speed of 0.2 m / min, and then the sheet is placed in an oven and vulcanized at 120°C for 2 min, and then the upper and lower release films are removed to form a carbon fiber-containing silicone rubber layer (150 μm thick);

[0087] 3) The carbon nanotube-loaded flaky copper powder is dispersed in ethanol, the ratio of the carbon nanotube-loaded flaky copper powder to ethanol is 1 g:3 mL, and then the mixture is uniformly sprayed on the surface of the carbon fiber-containing silicone rubber layer at a spraying speed of 10 mL / min, the spraying time is 40 s, and then the mixture is placed in an oven and heated at 70°C for 10 min to form a metal powder layer (40 μm thick);

[0088] 4) Apply the silicone rubber raw material mixture on the surface of the metal powder layer, and cover the polyester release film on the upper and lower surfaces, and then place between the two rollers of the calender machine to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven for vulcanization at 125°C for 5 min to form a carbon fiber-containing silicone rubber layer (thickness of 150 μm), and then remove the upper and lower release films to obtain the heat-conductive electromagnetic shielding silicone rubber composite film (thickness of 340 μm).

[0089] Example 4:

[0090] A heat-conductive electromagnetic shielding silicone rubber composite film (structure diagram as shown in Figure 1 The raw material composition of the heat-conductive electromagnetic shielding silicone rubber composite film is shown in the following table:

[0091] Table 4 Raw material composition table of a heat-conductive electromagnetic shielding silicone rubber composite film

[0092]

[0093]

[0094] The preparation method of the heat-conductive electromagnetic shielding silicone rubber composite film is as follows:

[0095] 1) Put the vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl silicone-palladium complex and ethynylcyclohexanol into a homogenizer, adjust the rotation speed of the homogenizer to 2000 rpm, mix for 40 s, and then place in a vacuum box, set the vacuum degree to 133 Pa, and vacuum for 20 min to obtain a silicone rubber raw material mixture;

[0096] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release film, and then place between the two rollers of the calender machine to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven for vulcanization at 120°C for 2 min, and then remove the upper and lower release films to form a carbon fiber-containing silicone rubber layer (thickness of 150 μm);

[0097] 3) Disperse the carbon nanotube-loaded sheet-shaped copper powder in ethanol, and the amount ratio of the carbon nanotube-loaded sheet-shaped copper powder to ethanol is 1 g:3 mL, and then uniformly spray on the surface of the carbon fiber-containing silicone rubber layer at a spraying speed of 10 mL / min for 50 s, and then place in an oven for heating at 70°C for 10 min to form a metal powder layer (thickness of 50 μm);

[0098] 4) Apply the silicone rubber raw material mixture on the surface of the metal powder layer, and cover the polyester release film on the upper and lower surfaces, and then place between the two rollers of the calender machine to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven for vulcanization at 125°C for 5 min to form a carbon fiber-containing silicone rubber layer (thickness of 150 μm), and then remove the upper and lower release films to obtain the heat-conductive electromagnetic shielding silicone rubber composite film (thickness of 350 μm).

[0099] Example 5:

[0100] A heat-conductive electromagnetic shielding silicone rubber composite film (structure diagram as shown in Figure 1 The raw material composition of the heat-conductive electromagnetic shielding silicone rubber composite film is shown in the following table:

[0101] Table 5 Raw material composition table of a heat-conductive electromagnetic shielding silicone rubber composite film

[0102]

[0103]

[0104] The preparation method of the above heat-conductive electromagnetic shielding silicone rubber composite film is as follows:

[0105] 1) Put the vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl silicone-palladium complex and ethynyl cyclohexanol into a homogenizer, adjust the rotation speed of the homogenizer to 2000 rpm, mix for 40 s, and then place in a vacuum box, set the vacuum degree to 133 Pa, and vacuum for 20 min to obtain a silicone rubber raw material mixture;

[0106] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release film, and then place between the two rollers of the calender machine to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven for vulcanization at 120°C for 2 min, and then remove the upper and lower release films to form a carbon fiber-containing silicone rubber layer (thickness of 150 μm);

[0107] 3) Disperse the carbon nanotube-loaded sheet-shaped copper powder in ethanol, and the amount ratio of the carbon nanotube-loaded sheet-shaped copper powder to ethanol is 1 g:3 mL, and then uniformly spray on the surface of the carbon fiber-containing silicone rubber layer at a spraying speed of 10 mL / min for 50 s, and then place in an oven for heating at 70°C for 10 min to form a metal powder layer (thickness of 50 μm);

[0108] 4) The silicon rubber raw material mixture is coated on the surface of the metal powder layer, and polyester release films are covered on the upper and lower surfaces. The two rollers of a calendering machine are used to make a sheet at a calendering speed of 0.2 m / min. The sheet is placed in an oven for vulcanization at 125°C for 5 min to form a carbon fiber-containing silicon rubber layer (150 μm thick). The upper and lower release films are removed to obtain a heat-conductive electromagnetic shielding silicon rubber composite film (350 μm thick).

[0109] Example 6:

[0110] A heat-conductive electromagnetic shielding silicon rubber composite film (structure diagram as shown in Figure 1 The raw material composition of the heat-conductive electromagnetic shielding silicon rubber composite film is shown in the following table.

[0111] Table 6 Raw material composition table of a heat-conductive electromagnetic shielding silicon rubber composite film

[0112]

[0113] The preparation method of the heat-conductive electromagnetic shielding silicon rubber composite film is as follows:

[0114] 1) The vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl silicone-palladium complex, and 3,5-dimethyl-1-hexyne-3-ol are added to a homogenizer. The rotation speed of the homogenizer is adjusted to 2000 rpm, and the mixture is mixed for 40 s. The mixture is then placed in a vacuum box, and the vacuum degree is set to 133 Pa. The vacuum is pumped for 20 min to obtain a silicon rubber raw material mixture.

[0115] 2) The upper and lower surfaces of the silicon rubber raw material mixture are covered with polyester release films. The two rollers of a calendering machine are used to make a sheet at a calendering speed of 0.2 m / min. The sheet is placed in an oven for vulcanization at 120°C for 2 min. The upper and lower release films are removed to form a carbon fiber-containing silicon rubber layer (150 μm thick).

[0116] 3) The carbon nanotube-loaded flaky copper powder is dispersed in ethanol. The amount ratio of the carbon nanotube-loaded flaky copper powder to ethanol is 1 g:3 mL. The powder is uniformly sprayed on the surface of the carbon fiber-containing silicon rubber layer at a spraying speed of 10 mL / min for 60 s. The mixture is then placed in an oven for heating at 70°C for 10 min to form a metal powder layer (60 μm thick).

[0117] 4) The silicon rubber raw material mixture is coated on the surface of the metal powder layer, and polyester release films are covered on the upper and lower surfaces. The two rollers of a calendering machine are used to make a sheet at a calendering speed of 0.2 m / min. The sheet is placed in an oven for vulcanization at 125°C for 5 min to form a carbon fiber-containing silicon rubber layer (150 μm thick). The upper and lower release films are removed to obtain a heat-conductive electromagnetic shielding silicon rubber composite film (360 μm thick).

[0118] The scanning electron microscope (SEM) image of the cross-section of the thermally conductive and electromagnetically shielding silicone rubber composite film in this embodiment is shown below. Figure 2 As shown.

[0119] Depend on Figure 2 It can be seen that the thermally conductive and electromagnetically shielding silicone rubber composite film is indeed composed of layers of silicone rubber containing carbon fibers, metal powder, and silicone rubber containing carbon fibers.

[0120] Comparative Example 1:

[0121] A silicone rubber composite film, the raw material composition of which is shown in the table below:

[0122] Table 7. Raw material composition of a silicone rubber composite film

[0123]

[0124] The preparation method of the above-mentioned silicone rubber composite film is as follows:

[0125] 1) Add vinyl silicone oil, hydrogen-containing silicone oil, sheet copper powder loaded with carbon nanotubes, platinum-tetrahydrofuran complex and ethynylcyclohexanol to a homogenizer, adjust the speed of the homogenizer to 2000 rpm, mix for 40 s, then place it in a vacuum chamber, set the vacuum degree to 133 Pa, and evacuate for 20 min to obtain a silicone rubber raw material mixture.

[0126] 2) Cover both the upper and lower surfaces of the silicone rubber raw material mixture with polyester release film, then place it between the two rollers of a calender and calender it into a thin sheet at a calendering speed of 0.2 m / min. Place the thin sheet in an oven at 125°C for 5 min to vulcanize, and then remove the upper and lower release films to obtain a silicone rubber composite film (thickness of 330 μm).

[0127] Comparative Example 2:

[0128] A silicone rubber composite film, the raw material composition of which is shown in the table below:

[0129] Table 8. Raw material composition of a silicone rubber composite film

[0130] Raw materials Amount (mass parts) Vinyl silicone oil (viscosity: 180 mPa-s) 100 Hydrogen-containing silicone oil (hydrogen content: 0.2%) 1 Carbon fiber (average length: 250 μm) 80 Methylvinylsiloxane-platinum complex 0.1 Ethynylcyclohexanol 0.01

[0131] The preparation method of the above-mentioned silicone rubber composite film is as follows:

[0132] 1) Add vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methyl vinyl siloxane-platinum complex and ethynyl cyclohexanol to a homogenizer, adjust the speed of the homogenizer to 2000 rpm, mix for 40 s, then place it in a vacuum chamber, set the vacuum degree to 133 Pa, and evacuate for 20 min to obtain a silicone rubber raw material mixture.

[0133] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release films, and place between the two rollers of a calender to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven to vulcanize at 125°C for 5 min, and then remove the upper and lower release films to obtain a silicone rubber composite film (330 μm thick).

[0134] Comparative Example 3

[0135] A silicone rubber composite film, whose raw material composition is shown in the following table:

[0136] Table 9 Raw material composition table of a silicone rubber composite film

[0137]

[0138]

[0139] The preparation method of the above silicone rubber composite film is as follows:

[0140] 1) Add vinyl silicone oil, hydrogen-containing silicone oil, carbon fiber, methylvinylsiloxane-platinum complex, and 3,6-dimethyl-1-heptyne-3-ol into a homogenizer, adjust the rotation speed of the homogenizer to 2000 rpm, and mix for 40 s, and then place in a vacuum tank, set the vacuum degree to 133 Pa, and vacuum for 20 min to obtain a silicone rubber raw material mixture;

[0141] 2) Cover the upper and lower surfaces of the silicone rubber raw material mixture with polyester release films, and place between the two rollers of a calender to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven to vulcanize at 120°C for 2 min, and then remove the upper and lower release films to form a silicone rubber layer containing carbon fibers (150 μm thick);

[0142] 3) Disperse flaky copper powder, carbon nanotubes, and 3-mercaptopropyltriethoxysilane in ethanol, and the ratio of the amounts of flaky copper powder, carbon nanotubes, 3-mercaptopropyltriethoxysilane, and ethanol is 9.62 g:0.38 g:0.1 g:30 mL, and then uniformly spray on the surface of the silicone rubber layer containing carbon fibers at a spraying speed of 10 mL / min for 30 s, and then place in an oven to heat at 70°C for 10 min to form a metal powder layer (30 μm thick);

[0143] 4) Coat the silicone rubber raw material mixture on the surface of the metal powder layer, and then cover the upper and lower surfaces with polyester release films, and place between the two rollers of a calender to make a sheet at a calendering speed of 0.2 m / min, and then place the sheet in an oven to vulcanize at 125°C for 5 min to form a silicone rubber layer containing carbon fibers (150 μm thick), and then remove the upper and lower release films to obtain a silicone rubber composite film (330 μm thick).

[0144] Performance testing:

[0145] 1) The electromagnetic shielding effectiveness test results of the thermally conductive electromagnetic shielding silicone rubber composite films of Examples 1-6 and the silicone rubber composite films of Comparative Examples 1-3 in the X-band are as follows: Figure 3 As shown;

[0146] 2) The test results of the thermal conductivity (out-of-plane thermal conductivity and in-plane thermal conductivity) of the thermally conductive and electromagnetically shielding silicone rubber composite films of Examples 1-6 and Comparative Examples 1-3 are as follows: Figure 4 As shown;

[0147] 3) The electromagnetic shielding effectiveness test results of the thermally conductive electromagnetic shielding silicone rubber composite film of Example 6 before and after 1500 cycles of 180° bending in the X-band are as follows: Figure 5 As shown;

[0148] 4) The test results of the comprehensive performance (thermal conductivity, electromagnetic shielding performance, and tensile strength) of the thermally conductive and electromagnetically shielding silicone rubber composite films of Examples 1-6 and Comparative Examples 1-3 are shown in the table below:

[0149] Table 10 Comprehensive performance test data of silicone rubber composite films of Examples 1-6 and Comparative Examples 1-3

[0150]

[0151]

[0152] Note:

[0153] Thermal conductivity: The thermal conductivity of the silicone rubber composite film was tested according to "GB / T 32064-2015 Thermal conductivity and thermal diffusivity of building materials by transient planar heat source test method". The thermal conductivity of the silicone rubber composite film was tested using a TPS2500S thermal constant analyzer from Hotdisk, Sweden. The probe was placed in the middle of the sample to be tested, ensuring that the sample and the probe were in close contact. Each sample was tested 3 times, and then the average value was taken.

[0154] Electromagnetic shielding performance (EMI SE): The electromagnetic parameters of the silicone rubber composite film were tested using a ZNB-20 vector network analyzer from Rohde & Schwarz GmbH, Germany, and the electromagnetic shielding effectiveness of the silicone rubber composite film was calculated. The test frequency range was 8.2 GHz to 12.4 GHz (X-band).

[0155] Tensile strength: The test was conducted in accordance with "GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" using a universal testing machine at a tensile rate of 200 mm / min.

[0156] Depend on Figures 3 to 5 As shown in Table 10:

[0157] a) The heat-conductive electromagnetic shielding silicone rubber composite films of Examples 1-6 are all composed of a silicone rubber layer containing carbon fibers, a metal powder layer (composed of flaky copper powder loaded with carbon nanotubes), and a silicone rubber layer containing carbon fibers, and all have excellent heat-conductive and electromagnetic shielding properties;

[0158] b) The silicone rubber composite film of Comparative Example 1 lacks a silicone rubber layer containing carbon fibers compared with the heat-conductive electromagnetic shielding silicone rubber composite films of Examples 1-6, the heat-conductive and conductive network is not perfect, the heat-conductive coefficient and electromagnetic shielding properties are both relatively low, in addition, the reinforcing effect of carbon fibers is also lacking, and the mechanical properties of the silicone rubber composite film are also poor;

[0159] c) The silicone rubber composite film of Comparative Example 2 lacks a metal powder layer compared with the heat-conductive electromagnetic shielding silicone rubber composite films of Examples 1-6, the heat-conductive coefficient, electromagnetic shielding properties, and mechanical properties are all decreased, because the metal powder layer can provide more heat-conductive network and multiple reflection loss, and can provide a large number of heterogeneous interfaces to increase interface polarization loss, thereby greatly improving the electromagnetic shielding properties of the silicone rubber composite film, in addition, the metal powder layer has good bonding with the silicone rubber, which can also improve the mechanical properties of the silicone rubber composite film;

[0160] d) The silicone rubber composite film of Comparative Example 3 has lower in-plane heat-conductive coefficient and lower electromagnetic shielding properties compared with the heat-conductive electromagnetic shielding silicone rubber composite films of Examples 1-6, because the carbon nanotubes and flaky copper powder are not interface-bonded by plasma ball milling, and both exist in a free state;

[0161] e) The heat-conductive electromagnetic shielding silicone rubber composite film of Example 2 has increased electromagnetic shielding efficiency and heat-conductive coefficient compared with the heat-conductive electromagnetic shielding silicone rubber composite film of Example 1, because the amount of flaky copper powder loaded with carbon nanotubes is increased;

[0162] f) The heat-conductive electromagnetic shielding silicone rubber composite film of Example 3 has increased electromagnetic shielding efficiency compared with the heat-conductive electromagnetic shielding silicone rubber composite film of Example 2, because the mass percentage of carbon fibers in the silicone rubber layer containing carbon fibers is increased;

[0163] g) The heat-conductive electromagnetic shielding silicone rubber composite film of Example 4 has increased electromagnetic shielding efficiency and heat-conductive coefficient compared with the heat-conductive electromagnetic shielding silicone rubber composite film of Example 3, because the amount of flaky copper powder loaded with carbon nanotubes is increased;

[0164] h) The heat-conductive electromagnetic shielding silicone rubber composite film of Example 5 has a higher mass percentage of carbon fibers in the silicone rubber layer containing carbon fibers, and both the electromagnetic shielding effectiveness and the thermal conductivity of the silicone rubber composite film are increased compared with the heat-conductive electromagnetic shielding silicone rubber composite film of Example 4;

[0165] i) The heat-conductive electromagnetic shielding silicone rubber composite film of Example 6 has a higher amount of sheet-shaped copper powder loaded with carbon nanotubes compared with the heat-conductive electromagnetic shielding silicone rubber composite film of Example 5, and both the electromagnetic shielding effectiveness and the thermal conductivity of the silicone rubber composite film are increased;

[0166] In summary, the heat-conductive electromagnetic shielding silicone rubber composite films of Examples 1-6 all have excellent heat-conductive performance and electromagnetic shielding performance, and the electromagnetic parameters of the silicone rubber composite films can be adjusted by changing the content of carbon fibers and the content of sheet-shaped copper powder loaded with carbon nanotubes, so that the heat-conductive performance, electromagnetic shielding effectiveness and mechanical performance of the silicone rubber composite films can be flexibly adjusted. In addition, the preparation process of the silicone rubber composite films is relatively simple, safe and environmentally friendly. Therefore, the silicone rubber composite films of the present application can be widely used in the fields of 5G communication, consumer electronics, power batteries, national defense and military industry, etc.

[0167] The above examples are preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A thermally conductive electromagnetic shielding silicone rubber composite film, characterized by, The application relates to a heat-conducting electromagnetic shielding silicone rubber composite film, which comprises a carbon-fiber-containing silicone rubber layer, a metal powder layer and a carbon-fiber-containing silicone rubber layer which are sequentially arranged in layers; the composition of the metal powder layer comprises flaky metal powder loaded with carbon materials; the flaky metal powder loaded with carbon materials is prepared by a preparation method comprising the following steps: mixing flaky metal powder, carbon materials, mercapto silane coupling agent and a solvent, performing plasma ball milling, and then drying to obtain the flaky metal powder loaded with carbon materials; the mass ratio of the flaky metal powder, the carbon materials, the mercapto silane coupling agent and the solvent is 10-30:1-5:0.10-1.25:0.1-0.

6.

2. The thermally-conductive, electromagnetically-shielded silicone rubber composite film of claim 1, wherein: The length of the carbon fibers is 50-300 mu m; the carbon materials in the flaky metal powder loaded with carbon materials are at least one of carbon nanotube powder, graphite powder and graphene powder, and the particle size of the carbon materials is 1-5 mu m; the flaky metal powder in the flaky metal powder loaded with carbon materials is at least one of flaky copper powder, flaky nickel powder and flaky silver powder, and the flake size of the flaky metal powder is 1-30 mu m.

3. The thermally conductive electromagnetic shielding silicone rubber composite film according to claim 1 or 2, characterized in that: The mass percentage of the carbon materials in the flaky metal powder loaded with carbon materials is 3-15%.

4. The thermally-conductive, electromagnetically-shielded silicone rubber composite film of claim 1, wherein: said mercapto silane coupling agent is gamma mercaptopropyltrimethoxysilane, gamma mercaptopropylmethyldimethoxysilane, 3 mercaptopropyltriethoxysilane.

5. The thermally-conductive, electromagnetic-shielding silicone rubber composite film according to claim 1 or 2, characterized by: The thickness of the carbon-fiber-containing silicone rubber layer is 50-200 mu m; and the thickness of the metal powder layer is 10-100 mu m.

6. The thermally-conductive, electromagnetic-shielding silicone rubber composite film according to claim 1 or 2, characterized by: The heat-conducting electromagnetic shielding silicone rubber composite film comprises the following components in parts by mass: vinyl silicone oil: 100 parts; hydrogen-containing silicone oil: 1-10 parts; carbon fibers: 10-200 parts; flaky metal powder loaded with carbon materials: 5-80 parts; platinum catalyst: 0.1-0.5 parts; inhibitor: 0.001-0.02 parts.

7. A process for preparing the thermally conductive electromagnetic shielding silicone rubber composite film according to claim 6, characterized by, The application further discloses a preparation method of the heat-conducting electromagnetic shielding silicone rubber composite film, which comprises the following steps: 1) mixing vinyl silicone oil, hydrogen-containing silicone oil, carbon fibers, a platinum catalyst and an inhibitor uniformly, and then performing defoaming to obtain a silicone rubber raw material mixture; 2) pressing the silicone rubber raw material mixture into a flaky shape and then performing vulcanization to form a carbon-fiber-containing silicone rubber layer; 3) dispersing the flaky metal powder loaded with carbon materials in a solvent, coating the flaky metal powder loaded with carbon materials on the surface of the carbon-fiber-containing silicone rubber layer, and then performing drying to form a metal powder layer; 4) coating the silicone rubber raw material mixture on the surface of the metal powder layer and pressing the silicone rubber raw material mixture into a flaky shape, and then performing vulcanization to obtain the heat-conducting electromagnetic shielding silicone rubber composite film.

8. An electronic device, comprising: The application further discloses a heat-conducting electromagnetic shielding silicone rubber composite film containing the heat-conducting electromagnetic shielding silicone rubber composite film.

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