Curable silicone rubber composition and preparation method thereof
A silicone rubber composition made of hollow silica microspheres, boron nitride nanosheets, and a specific siloxane mixture solves the problems of dielectric constant and loss at high frequencies, achieving a balance between low dielectric properties and mechanical strength, making it suitable for high-frequency electronic devices.
Patent Information
- Application Number
- CN202511853206.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-02-27
AI Technical Summary
The dielectric constant of existing platinum-catalyzed vulcanized silicone rubber is between 2.8 and 3.2, and the dielectric loss factor is on the order of 10⁻³, which is difficult to meet the requirements of high-frequency applications. Furthermore, existing methods for reducing the dielectric constant may affect mechanical strength or increase high-frequency loss.
A silicone rubber composition was prepared by using hollow silica microspheres and boron nitride nanosheets as functional fillers, combined with vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, and using platinum catalysts and inhibitors through a specific mixing and curing process.
It achieves both low dielectric constant and low dielectric loss at high frequencies, maintains mechanical strength, and possesses excellent heat aging resistance and electrochemical reliability.
Smart Images
Figure CN121574561A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic packaging materials technology, specifically to a silicone rubber material suitable for packaging high-frequency, high-speed electronic devices, and particularly to a platinum-catalyzed vulcanized silicone rubber composition with low dielectric constant and low dielectric loss factor and its preparation method. Background Technology
[0002] Silicone rubber is widely used in electronic packaging due to its excellent flexibility, heat resistance, and electrical insulation properties. While traditional platinum-catalyzed vulcanized silicone rubber has high purity, its dielectric constant is typically between 2.8 and 3.2, and its dielectric loss factor is around 10. -3 The current level is insufficient to meet the needs of higher frequency (e.g., >10GHz) applications.
[0003] In existing technologies, the dielectric constant of traditional platinum-catalyzed vulcanized silicone rubber is mostly reduced by adding porous inorganic fillers or fluorination modification. However, this often faces the following problems: adding porous inorganic fillers will significantly reduce the mechanical strength of the material and easily cause the rubber compound to crack when mixed with the silicone rubber matrix, thus leading to unstable performance; fluorination modification is costly and may inhibit the activity of platinum catalyst, which will seriously affect the vulcanization efficiency.
[0004] As electronic technology advances towards higher frequencies and higher speeds, signal transmission delay and loss have become key factors limiting performance. Signal delay is proportional to the square root of the dielectric constant, while signal loss is closely related to the product of the dielectric constant and the dielectric loss factor. Simply reducing the dielectric constant often fails to simultaneously achieve low dielectric loss, and may even lead to increased high-frequency loss due to the introduction of interface polarization. Therefore, developing packaging materials that combine low dielectric constant and low dielectric loss is crucial. Summary of the Invention
[0005] This application provides a cured silicone rubber composition with both low dielectric constant and low dielectric loss, and a method for preparing the same.
[0006] This application provides a curable silicone rubber composition, comprising, by weight: 100 parts of a silicone rubber matrix; a crosslinking agent, wherein the crosslinking agent is a polysiloxane containing Si-H bonds, and the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; a platinum catalyst, wherein the amount of platinum catalyst added is 10-100 ppm based on the platinum metal content of the total weight of the silicone rubber composition; 0.01-0.1 parts of an inhibitor, wherein the inhibitor includes at least one selected from methylbutyninol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-etynyl-1-cyclohexanol trimethylsilyl ether; and 20-35 parts of a functional filler, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 5-25 parts and the boron nitride nanosheets are 10-15 parts.
[0007] In some embodiments of this application, the silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane is 80-95 parts and the vinyl-terminated polymethylphenylsiloxane is 5-20 parts.
[0008] In some embodiments of this application, the crosslinking agent has a Si-H bond content of 0.15 to 0.35%.
[0009] In some embodiments of this application, the platinum catalyst is bis(divinyltetramethyldisiloxane)platinum.
[0010] In some embodiments of this application, the hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, and the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.
[0011] Another aspect of this application provides a method for preparing a cured silicone rubber composition. The method includes: mixing a silicone rubber matrix under vacuum at a speed of 50-80 rpm for at least 15 minutes; then adding a functional filler; controlling the temperature at 20-40°C and mixing under vacuum at a speed of less than or equal to 30 rpm for at least 30 minutes; then dispersing at a speed of greater than 90 rpm for 15-45 minutes to ensure that the functional filler is uniformly dispersed and its structure remains unchanged; adding a crosslinking agent and an inhibitor; controlling the temperature at 20-40°C and mixing under vacuum at a speed of 50-80 rpm for at least 15 minutes; adding a platinum catalyst; controlling the temperature at 20-40°C and mixing under vacuum at a speed of no more than 10 rpm for at least 5 minutes; and discharging the material to obtain the silicone rubber composition.
[0012] In some embodiments of this application, the preparation method of the curable silicone rubber composition further includes: curing at a temperature of 100-150°C for 10-30 minutes to cure the silicone rubber composition into shape.
[0013] In some embodiments of this application, the silicone rubber matrix is 100 parts by weight; the crosslinking agent is a polysiloxane containing Si-H bonds, wherein the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; the amount of platinum catalyst added is 10-100 ppm of the total weight of the silicone rubber composition, calculated based on the platinum metal content; the inhibitor is 0.01-0.1 parts, and the inhibitor includes at least one selected from methylbutyninol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-etynyl-1-cyclohexanol trimethylsilyl ether; the functional filler is 20-35 parts, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 5-25 parts and the boron nitride nanosheets are 10-15 parts.
[0014] In some embodiments of this application, the silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane is 80-95 parts and the vinyl-terminated polymethylphenylsiloxane is 5-20 parts.
[0015] In some embodiments of this application, the hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, and the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.
[0016] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0017] The hollow structure of hollow silica microspheres allows for the introduction of air (approximately 1%), effectively reducing the dielectric constant. Furthermore, the chemical composition of hollow silica microspheres is silica, which has a certain interaction force with silicone rubber, ensuring good dispersion within the silicone rubber and forming a relatively strong interface with the matrix. This reduces the increase in dielectric loss and stress concentration caused by interface defects.
[0018] Boron nitride itself has an extremely low dielectric constant (about 4) and low power loss. Its sheet-like structure can form a physical barrier in the substrate, extending the electric field path. At the same time, its excellent thermal conductivity helps to dissipate the heat generated during high-frequency operation and prevents the increase of heat-induced loss.
[0019] Adding vinyl-terminated polymethylphenylsiloxane to vinyl-terminated polydimethylsiloxane can introduce phenyl groups into the silicone rubber matrix. By utilizing their large volume and steric hindrance, the polarization rate of the siloxane chain segments can be reduced. At the same time, the introduction of phenyl groups helps to suppress the orientation polarization of the molecular chains under an electric field, thereby reducing dielectric loss.
[0020] The platinum-catalyzed sulfidation system ensures a pure product free of byproducts, exhibiting excellent heat aging resistance and electrochemical reliability, and meeting the long-term use requirements of high-frequency electronic devices. Attached Figure Description
[0021] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:
[0022] Figure 1 This is the dielectric impedance diagram of Embodiment 3 of this application;
[0023] Figure 2 This is the dielectric echo pattern of Embodiment 3 of this application;
[0024] Figure 3 This is a dielectric attenuation pattern of Embodiment 3 of this application. Detailed Implementation
[0025] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.
[0026] This application provides a curable silicone rubber composition, comprising, by weight: 100 parts of a silicone rubber matrix; a crosslinking agent, wherein the crosslinking agent is a polysiloxane containing Si-H bonds, and the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; a platinum catalyst, wherein the amount of platinum catalyst added is 10-100 ppm based on the platinum metal content of the total weight of the silicone rubber composition; 0.01-0.1 parts of an inhibitor, wherein the inhibitor includes at least one selected from methylbutyninol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-etynyl-1-cyclohexanol trimethylsilyl ether; and 20-35 parts of a functional filler, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 5-25 parts and the boron nitride nanosheets are 10-15 parts.
[0027] In some embodiments of this application, the cured silicone rubber composition comprises, by weight, 100 parts of silicone rubber matrix; a crosslinking agent, wherein the crosslinking agent is a polysiloxane containing Si-H bonds, and the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is 1.2:1; a platinum catalyst, wherein the amount of platinum catalyst added is 50 ppm of the total weight of the silicone rubber composition, calculated based on the platinum metal content; 0.08 parts of an inhibitor, wherein the inhibitor is methylbutyninol; and 25 parts of a functional filler, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 20 parts and the boron nitride nanosheets are 5 parts.
[0028] In some embodiments of this application, the silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane comprises 80-95 parts and the vinyl-terminated polymethylphenylsiloxane comprises 5-20 parts. For example, the vinyl-terminated polydimethylsiloxane comprises 85 parts and the vinyl-terminated polymethylphenylsiloxane comprises 15 parts.
[0029] In some embodiments of this application, the crosslinking agent has a Si-H bond content of 0.15% to 0.35%, such as 0.2% or 0.3%.
[0030] In some embodiments of this application, the platinum catalyst is bis(divinyltetramethyldisiloxane)platinum.
[0031] In some embodiments of this application, the hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, and the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.
[0032] Another aspect of this application provides a method for preparing a cured silicone rubber composition. The method includes: mixing a silicone rubber matrix under vacuum at a speed of 50-80 rpm for at least 15 minutes, wherein the mixing equipment is, for example, a planetary mixer; then adding a functional filler; controlling the temperature at 20-40°C and mixing under vacuum at a speed of less than or equal to 30 rpm for at least 30 minutes; then dispersing at a speed greater than 90 rpm for 15-45 minutes to ensure that the functional filler is uniformly dispersed and its structure remains unchanged, meaning that the structure of the functional filler is not destroyed during the mixing process; adding a crosslinking agent and an inhibitor; controlling the temperature at 20-40°C and mixing under vacuum at a speed of 50-80 rpm for at least 15 minutes; adding a platinum catalyst; controlling the temperature at 20-40°C and mixing under vacuum at a speed of no more than 10 rpm for at least 5 minutes. The reason for using the lower speed and lower mixing time is to avoid premature reaction; and discharging the material to obtain the silicone rubber composition.
[0033] In some embodiments of this application, the preparation method of the curable silicone rubber composition further includes: curing at a temperature of 100-150°C for 10-30 minutes to cure the silicone rubber composition into shape.
[0034] In some embodiments of this application, the silicone rubber matrix is 100 parts by weight; the crosslinking agent is a polysiloxane containing Si-H bonds, wherein the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; the amount of platinum catalyst added is 10-100 ppm of the total weight of the silicone rubber composition, calculated based on the platinum metal content; the inhibitor is 0.01-0.1 parts, and the inhibitor includes at least one selected from methylbutyninol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-etynyl-1-cyclohexanol trimethylsilyl ether; the functional filler is 20-35 parts, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 5-25 parts and the boron nitride nanosheets are 10-15 parts.
[0035] In some embodiments of this application, the cured silicone rubber composition comprises, by weight, 100 parts of silicone rubber matrix; a crosslinking agent, wherein the crosslinking agent is a polysiloxane containing Si-H bonds, and the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is 1.4:1; a platinum catalyst, wherein the amount of platinum catalyst added is 80 ppm of the total weight of the silicone rubber composition, calculated based on the platinum metal content; 0.06 parts of an inhibitor, wherein the inhibitor is methylbutyninol; and 23 parts of a functional filler, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres comprise 15 parts and the boron nitride nanosheets comprise 7 parts.
[0036] In some embodiments of this application, the silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane comprises 80-95 parts and the vinyl-terminated polymethylphenylsiloxane comprises 5-20 parts. For example, the vinyl-terminated polydimethylsiloxane comprises 90 parts and the vinyl-terminated polymethylphenylsiloxane comprises 10 parts.
[0037] In some embodiments of this application, the hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, and the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.
[0038] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0039] The hollow structure of hollow silica microspheres allows for the introduction of air (approximately 1%), effectively reducing the dielectric constant. Furthermore, the chemical composition of hollow silica microspheres is silica, which has a certain interaction force with silicone rubber, ensuring good dispersion within the silicone rubber and forming a relatively strong interface with the matrix. This reduces the increase in dielectric loss and stress concentration caused by interface defects.
[0040] Boron nitride itself has an extremely low dielectric constant (about 4) and low power loss. Its sheet-like structure can form a physical barrier in the substrate, extending the electric field path. At the same time, its excellent thermal conductivity helps to dissipate the heat generated during high-frequency operation and prevents the increase of heat-induced loss.
[0041] Adding vinyl-terminated polymethylphenylsiloxane to vinyl-terminated polydimethylsiloxane can introduce phenyl groups into the silicone rubber matrix. By utilizing their large volume and steric hindrance, the polarization rate of the siloxane chain segments can be reduced. At the same time, the introduction of phenyl groups helps to suppress the orientation polarization of the molecular chains under an electric field, thereby reducing dielectric loss.
[0042] The platinum-catalyzed sulfidation system ensures a pure product free of byproducts, exhibiting excellent heat aging resistance and electrochemical reliability, and meeting the long-term use requirements of high-frequency electronic devices.
[0043] Example 1:
[0044] The following components were weighed separately according to weight: 100 parts of silicone rubber matrix (a mixture of 95 parts of vinyl-terminated polydimethylsiloxane and 5 parts of vinyl-terminated polymethylphenylsiloxane), 1.2 parts of crosslinking agent (polysiloxane with a Si-H bond content of 0.15%, the Si-H bond content being a molar ratio of 1:1 to the vinyl group in the silicone rubber matrix), 0.02 parts of platinum catalyst (platinum metal being 10 ppm of the total weight of the silicone rubber composition), 0.01 parts of inhibitor (methylbutynedol), and 20 parts of functional filler (a mixture of 5 parts of hollow silica microspheres with an average particle size of 1 μm and a shell thickness of 0.2 μm, and 15 parts of boron nitride nanosheets with a transverse dimension of 0.5 μm and a thickness of 50 nm). After weighing, the silicone rubber matrix was mixed in a planetary mixer at 50 rpm under vacuum for 15 minutes. Then, functional fillers were added, and the mixture was stirred at 30 rpm under vacuum for 30 minutes at a controlled temperature of 20°C, followed by dispersion at 90 rpm for 15 minutes. Next, crosslinking agents and inhibitors were added, and the mixture was stirred at 50 rpm under vacuum for 15 minutes at a controlled temperature of 20°C. Finally, platinum catalyst was added, and the mixture was stirred at 10 rpm under vacuum for 5 minutes at a controlled temperature of 20°C. The resulting silicone rubber composition was then discharged. This silicone rubber composition was cured at 100°C for 10 minutes to form test strips, and its dielectric properties were tested using a network analyzer combined with the resonant cavity method.
[0045] Example 2:
[0046] The following components were weighed separately according to weight: 100 parts of silicone rubber matrix (a mixture of 90 parts of vinyl-terminated polydimethylsiloxane and 10 parts of vinyl-terminated polymethylphenylsiloxane), 1.4 parts of crosslinking agent (polysiloxane with a Si-H bond content of 0.20%, the Si-H bond content being a molar ratio of 1.2:1 to the vinyl group in the silicone rubber matrix), 0.06 parts of platinum catalyst (platinum metal at 30 ppm of the total weight of the silicone rubber composition), 0.02 parts of inhibitor (ethynylcyclohexanol), and 25 parts of functional filler (a mixture of 8 parts of hollow silica microspheres with an average particle size of 3 μm and a shell thickness of 0.2 μm, and 17 parts of boron nitride nanosheets with a transverse dimension of 2 μm and a thickness of 100 nm). After weighing, the silicone rubber matrix was mixed in a planetary mixer at 60 rpm under vacuum for 20 min. Then, functional fillers were added, and the mixture was stirred at 25 rpm under vacuum for 40 min, controlled at 30℃, followed by dispersion at 100 rpm for 25 min. Next, crosslinking agents and inhibitors were added, and the mixture was stirred at 60 rpm under vacuum for 20 min, controlled at 30℃. Finally, platinum catalyst was added, and the mixture was stirred at 8 rpm under vacuum for 3 min, controlled at 30℃, before being discharged to obtain the silicone rubber composition. This silicone rubber composition was cured at 120℃ for 12 min to form test strips, and its dielectric properties were tested using a network analyzer combined with the resonant cavity method.
[0047] Example 3:
[0048] The following components were weighed separately according to weight: 100 parts of silicone rubber matrix (a mixture of 85 parts of vinyl-terminated polydimethylsiloxane and 15 parts of vinyl-terminated polymethylphenylsiloxane), 1.5 parts of crosslinking agent (polysiloxane with a Si-H bond content of 0.25%, the Si-H bond content being a molar ratio of 1.3:1 to the vinyl group in the silicone rubber matrix), 0.1 parts of platinum catalyst (platinum metal at 50 ppm of the total weight of the silicone rubber composition), 0.05 parts of inhibitor (ethynylcyclohexanol), and 30 parts of functional filler (a mixture of 12 parts of hollow silica microspheres with an average particle size of 5 μm and a shell thickness of 0.3 μm, and 18 parts of boron nitride nanosheets with a transverse dimension of 3 μm and a thickness of 150 nm). After weighing, the silicone rubber matrix was mixed in a planetary mixer at 70 rpm under vacuum for 20 minutes. Then, functional fillers were added, and the mixture was stirred at 20 rpm under vacuum for 40 minutes, controlled at 40°C, followed by dispersion at 120 rpm for 30 minutes. Next, crosslinking agents and inhibitors were added, and the mixture was stirred at 65 rpm under vacuum for 25 minutes, controlled at 40°C. Finally, platinum catalyst was added, and the mixture was stirred at 8 rpm under vacuum for 3 minutes, controlled at 40°C, to obtain the silicone rubber composition. This silicone rubber composition was cured at 135°C for 20 minutes to form test strips, and its dielectric properties were tested using a network analyzer with a resonant cavity method. Figure 1 This is the dielectric impedance diagram of Embodiment 3 of this application; Figure 2 This is the dielectric echo pattern of Embodiment 3 of this application; Figure 3 This is a dielectric attenuation pattern of Embodiment 3 of this application.
[0049] Example 4:
[0050] The following components were weighed separately according to weight: 100 parts of silicone rubber matrix (a mixture of 85 parts of vinyl-terminated polydimethylsiloxane and 15 parts of vinyl-terminated polymethylphenylsiloxane), 1.5 parts of crosslinking agent (polysiloxane with a Si-H bond content of 0.25%, the Si-H bond content being a molar ratio of 1.3:1 to the vinyl group in the silicone rubber matrix), 0.15 parts of platinum catalyst (platinum metal being 75 ppm of the total weight of the silicone rubber composition), 0.05 parts of inhibitor (1-ethynyl-1-cyclohexanol trimethylsilyl ether), and 35 parts of functional filler (a mixture of 15 parts of hollow silica microspheres with an average particle size of 7 μm and a shell thickness of 0.5 μm, and 20 parts of boron nitride nanosheets with a transverse dimension of 3 μm and a thickness of 200 nm). After weighing, the silicone rubber matrix was mixed in a planetary mixer at 80 rpm under vacuum for 20 min. Then, functional fillers were added, and the mixture was stirred at 20 rpm under vacuum for 40 min, controlled at 30℃, followed by dispersion at 100 rpm for 45 min. Next, crosslinking agents and inhibitors were added, and the mixture was stirred at 80 rpm under vacuum for 25 min, controlled at 30℃. Finally, platinum catalyst was added, and the mixture was stirred at 6 rpm under vacuum for 4 min, controlled at 30℃, before being discharged to obtain the silicone rubber composition. This silicone rubber composition was cured at 130℃ for 20 min to form test strips, and its dielectric properties were tested using a network analyzer combined with the resonant cavity method.
[0051] Example 5:
[0052] The following components were weighed separately according to weight: 100 parts of silicone rubber matrix (a mixture of 80 parts of vinyl-terminated polydimethylsiloxane and 20 parts of vinyl-terminated polymethylphenylsiloxane), 1.7 parts of crosslinking agent (polysiloxane with a Si-H bond content of 0.3% and a Si-H bond content in a molar ratio of 1.5:1 to the vinyl group in the silicone rubber matrix), 0.25 parts of platinum catalyst (platinum metal at 100 ppm of the total weight of the silicone rubber composition), 0.1 parts of inhibitor (tetramethylethylenediamine), and 35 parts of functional filler (a mixture of 25 parts of hollow silica microspheres with an average particle size of 10 μm and a shell thickness of 0.3 μm and 15 parts of boron nitride nanosheets with a transverse dimension of 5 μm and a thickness of 150 nm). After weighing, the silicone rubber matrix was mixed in a planetary mixer at 60 rpm under vacuum for 30 min. Then, functional fillers were added, and the mixture was stirred at 20 rpm under vacuum for 40 min, controlled at 30℃, followed by dispersion at 100 rpm for 60 min. Next, crosslinking agents and inhibitors were added, and the mixture was stirred at 60 rpm under vacuum for 30 min, controlled at 30℃. Finally, platinum catalyst was added, and the mixture was stirred at 6 rpm under vacuum for 5 min, controlled at 30℃, and then discharged to obtain the silicone rubber composition. This silicone rubber composition was cured at 150℃ for 12 min to form test strips, and its dielectric properties were tested using a network analyzer combined with the resonant cavity method.
[0053] Table 1. Dielectric properties of the examples
[0054]
[0055] As can be seen from Table 1, each embodiment has extremely low dielectric constant and dielectric loss, and can still have both low dielectric constant and low dielectric loss even at high frequencies >10GHz.
[0056] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments of this application. Other modified embodiments are also within the scope of this application. Therefore, the embodiments disclosed herein are merely examples and not limitations. Those skilled in the art can adopt alternative configurations to implement the applications in this application based on the embodiments in this application. Therefore, the embodiments of this application are not limited to those embodiments precisely described in the application.
Claims
1. A curable silicone rubber composition, characterized in that, by weight parts, include: 100 parts silicone rubber matrix, A crosslinking agent, wherein the crosslinking agent is a polysiloxane containing Si-H bonds, and the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; The platinum catalyst, calculated based on the platinum metal content, is added in an amount of 10 to 100 ppm of the total weight of the silicone rubber composition. 0.01 to 0.1 parts of inhibitor, said inhibitor comprising at least one of methylbutynol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-ethynyl-1-cyclohexanol trimethylsilyl ether; 20-35 parts of functional filler, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres are 5-25 parts and the boron nitride nanosheets are 10-15 parts.
2. The cured silicone rubber composition according to claim 1, characterized in that, include: The silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane comprises 80-95 parts and the vinyl-terminated polymethylphenylsiloxane comprises 5-20 parts.
3. The cured silicone rubber composition as described in claim 1, characterized in that, The mass percentage content of Si-H bonds in the crosslinking agent is 0.15 to 0.35%.
4. The cured silicone rubber composition according to claim 1, characterized in that, The platinum catalyst is bis(divinyltetramethyldisiloxane)platinum.
5. The cured silicone rubber composition as described in claim 1, characterized in that, The hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, while the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.
6. A method for preparing a curable silicone rubber composition, characterized in that, The method includes: The silicone rubber matrix is mixed in a vacuum at a speed of 50-80 rpm for more than 15 minutes. Then, functional fillers are added, and the temperature is controlled at 20-40℃. The mixture is then mixed in a vacuum at a speed of less than or equal to 30 rpm for more than 30 minutes. Finally, it is dispersed at a speed of more than 90 rpm for 15-45 minutes to ensure that the functional fillers are uniformly dispersed and their structure remains unchanged. Add crosslinking agent and inhibitor, control the temperature at 20-40℃, mix at a speed of 50-80 rpm for more than 15 minutes under vacuum conditions; Add a platinum catalyst, control the temperature at 20-40℃, and mix for no more than 5 minutes under vacuum at a speed not exceeding 10 rpm; The silicone rubber composition is obtained by discharging the material.
7. The method for preparing the curable silicone rubber composition according to claim 6, characterized in that, The method further includes curing the silicone rubber composition at a temperature of 100-150°C for 10-30 minutes to solidify it.
8. The method for preparing the curable silicone rubber composition according to claim 6, characterized in that, The silicone rubber matrix comprises 100 parts by weight; the crosslinking agent is a polysiloxane containing Si-H bonds, wherein the molar ratio of Si-H bonds in the polysiloxane to vinyl groups in the silicone rubber matrix is (1.0-1.5):1; the amount of platinum catalyst added, calculated based on the platinum metal content, is 10-100 ppm of the total weight of the silicone rubber composition; the inhibitor comprises 0.01-0.1 parts, wherein the inhibitor includes at least one selected from methylbutyninol, etynylcyclohexanol, benzonitrile, tetramethylethylenediamine, and 1-etynyl-1-cyclohexanol trimethylsilyl ether; the functional filler comprises 20-35 parts, wherein the functional filler is a mixture of hollow silica microspheres and boron nitride nanosheets, wherein the hollow silica microspheres comprise 5-25 parts and the boron nitride nanosheets comprise 10-15 parts.
9. The method for preparing the curable silicone rubber composition according to claim 7, characterized in that, The silicone rubber matrix is a mixture of vinyl-terminated polydimethylsiloxane and vinyl-terminated polymethylphenylsiloxane, wherein the vinyl-terminated polydimethylsiloxane comprises 80-95 parts and the vinyl-terminated polymethylphenylsiloxane comprises 5-20 parts.
10. The method for preparing the curable silicone rubber composition according to claim 7, characterized in that, The hollow silica microspheres have an average particle size of 1–10 μm and a shell thickness of 0.2–0.5 μm, while the boron nitride nanosheets have a lateral dimension of 0.5–5 μm and a thickness of 50–200 nm.