High-performance silicone rubber as well as preparation method and application thereof

Abstract

The invention discloses high-performance silicone rubber as well as a preparation method and application thereof, and relates to the technical field of high polymer materials. According to the high-performance silicon rubber provided by the invention, the nano boron nitride with a specific size and the gas-phase method white carbon black are used as heat-conducting fillers, and meanwhile, the nano magnesium hydroxide with a specific size, the ammonium polyphosphate and the melamine cyanurate are used as flame retardants together, so that the high-performance silicon rubber is prepared by utilizing the synergistic effect of different fillers and the flame retardants; the insulating property, flame retardance, heat conduction, mechanical property and other properties of the silicone rubber are comprehensively improved, the tensile strength of the obtained silicone rubber is larger than 4 MPa, the elongation at break reaches 180% or above, the minimum heat conductivity coefficient reaches 1.5 W / m.k or above, the volume resistivity reaches 1.0 * 10 < 12 > omega.cm, the flame retardant rating reaches UL-V0, the heat conduction property, the insulating property, the flame retardance and the mechanical property are excellent, and the silicone rubber can be widely applied to the field of silicone rubber. The method is suitable for preparing sealing materials in the fields of electronics, automobile industry, aerospace, buildings and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a high-performance silicone rubber and a preparation method and application thereof. Background Art

[0002] As an important type of polymer elastomer material, silicone rubber has been widely used in many fields such as aerospace, aviation, electronics, and electrical appliances due to its excellent high and low temperature resistance, flexibility, and electrical insulation, especially in the field of heat dissipation and heat transfer. However, in recent years, with the rapid development of modern science and technology, the performance requirements of silicone rubber in various industries have become increasingly stringent. For example, in the power cable system, silicone rubber is required to work for a long time in an environment where the cable operating temperature is around 90°C (the temperature may rise by more than 100°C in case of failure); in the field of new energy vehicles, since the battery will generate heat during the charging and discharging process, silicone rubber seals and other components are required to maintain good sealing performance and physical and chemical stability in an environment of 80°C-100°C for a long time to ensure the safe operation of the battery system. The development of information technology has increased people's demand and dependence on electronic products. In this context, how to improve the safety of electronic products and their components and ensure people's experience in daily use has received more and more attention.

[0003] At present, insulating thermally conductive silicone rubber is often used for sealing and packaging in electronic products to improve their heat dissipation and safety. However, the short-circuit accidents of electronic components reported recently are increasing. For example, according to statistics from an authoritative electrical safety research institution, in the five years from 2020 to 2024, due to the insufficient flame retardant performance of silicone rubber, there were more than 500 accidents of fires caused by short circuits of electronic components, and the direct economic losses were as high as 120 million yuan. To avoid serious accidents when electronic products are short-circuited, improving the flame retardant properties of silicone rubber is a feasible way. At the same time, in order to ensure the reliability during use, attention should also be paid to how to improve the mechanical properties of silicone rubber. Therefore, how to modify silicone rubber, such as introducing specific groups or structures on the silicone rubber molecular chain through chemical reactions, introducing groups containing flame retardant elements such as phosphorus and nitrogen to enhance flame retardancy, or introducing rigid groups to improve mechanical properties, in order to obtain silicone rubber with better thermal conductivity, flame retardancy, insulation and mechanical properties, has become an urgent problem to be solved. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the present invention provides a high-performance silicone rubber, which utilizes nano boron nitride and fumed silica of a specific size as thermal conductive fillers, and simultaneously utilizes nano magnesium hydroxide with an average particle size of 30 to 500 nm together with APP (ammonium polyphosphate) and MCA (melamine cyanurate) as flame retardants, and utilizes the synergistic effect between different fillers and flame retardants to achieve comprehensive improvement of the insulation, flame retardancy, thermal conductivity, mechanical properties and other properties of the silicone rubber.

[0005] Another object of the present invention is to provide a method for preparing high-performance silicone rubber and its application in sealing materials.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0007] A high-performance silicone rubber, comprising the following raw materials calculated by weight:

[0008] 100 parts of vinyl-terminated polydimethylsiloxane, 8-14 parts of cross-linking agent, 33-43 parts of thermal conductive filler, 19.5-27.5 parts of flame retardant, 0.2-0.4 parts of catalyst, 0.8-1.3 parts of inhibitor;

[0009] The thermal conductive filler comprises nano boron nitride and fumed silica;

[0010] The flame retardant includes nano magnesium hydroxide, ammonium polyphosphate and melamine cyanurate;

[0011] The average lateral size of the nano boron nitride is 60 to 80 nm;

[0012] The specific surface area of ​​the fumed silica is 140 to 170 m 2 / g;

[0013] The average lateral size of the nano magnesium hydroxide is 40-65 nm.

[0014] The inventors of this application have found through a large number of experimental studies that the use of nano boron nitride (sheet-shaped, with a thickness range of 20 to 50 nm) with an average lateral size of 60 to 80 nm and a specific surface area of ​​140 to 170 m 2 / g of fumed silica as a thermally conductive filler can form a rich and coherent thermal conductive path in the silicone rubber matrix, thereby improving the thermal conductivity of silicone rubber. At the same time, the use of nano magnesium hydroxide with an average lateral size of 40 to 65nm (thickness range is also 20 to 50nm) together with APP (ammonium polyphosphate) and MCA (melamine cyanurate) as flame retardants can further improve the integrity and continuity of the thermal conductive path while improving the flame retardancy of silicone rubber, thereby improving the thermal conductivity of silicone rubber. From a theoretical perspective, this synergistic effect is reflected in many aspects. In terms of thermal conductivity, nano boron nitride has extremely high intrinsic thermal conductivity, and its unique two-dimensional layered structure can form an effective thermal conductive path in the silicone rubber matrix. Fumed silica can not only improve the processing and mechanical properties of silicone rubber, but its nanoscale size also helps to fill the gaps between boron nitride particles, reduce phonon scattering, and cooperate with boron nitride to enable heat to be transferred more efficiently in the material, thereby significantly improving the thermal conductivity of silicone rubber.

[0015] In terms of flame retardancy, nano magnesium hydroxide absorbs a large amount of heat when it is decomposed by heat, which plays a role in cooling the polymer matrix. At the same time, the magnesium oxide produced by the decomposition forms a dense protective film on the surface of the material, blocking the transfer of oxygen and heat. APP will decompose to form polyphosphoric acid when heated. Polyphosphoric acid has a strong dehydration effect, which promotes the carbonization of the silicone rubber surface to form a carbon layer. The non-combustible gases such as ammonia produced by the decomposition of MCA can dilute the concentration of combustible gases. At the same time, the melamine and cyanuric acid produced by the decomposition will form an expansive carbon layer at high temperatures. Nano magnesium hydroxide, APP and MCA cooperate with each other, synergistically working from multiple angles such as absorbing heat and cooling, blocking oxygen and heat, diluting combustible gases, and promoting the formation of carbon layers, greatly improving the flame retardant properties of silicone rubber.

[0016] On the basis of the above, a flame retardant and a thermally conductive filler which are combined with specific substances are added to the silicone rubber system. There are certain interactions between them and the silicone rubber molecular chains, such as chemical bonding, physical adsorption, etc. This interaction makes the molecular chains of silicone rubber more regularly arranged, strengthens the intermolecular forces, and can also hinder the transmission of electrons and produce a similar effect of fine crystal strengthening in the matrix, thereby greatly improving the insulation and mechanical properties of silicone rubber. In this process, if the sizes of nano boron nitride, fumed silica and nano magnesium hydroxide are not appropriate, or the amount of thermally conductive filler and flame retardant added to the matrix is ​​not appropriate, or if the specific filler in the present invention is replaced by other fillers with similar properties, the combined effect of thermally conductive filler and flame retardant will decrease. It is speculated that this may be because there is better compatibility between the specific fillers selected in the present invention.

[0017] In a specific embodiment of the present invention, the average lateral size of the nano magnesium hydroxide and nano boron nitride refers to the length of the side of the maximum circumscribed rectangle of the nano material. More specifically, the average lateral size of the nano material is obtained by SEM observation and measurement. More specifically, the average lateral size of the nano material is obtained by observation and measurement under the condition of SEM magnification of 50000×, and the average lateral size is obtained by making the maximum circumscribed rectangle of 100 nano materials under SEM and taking the average value of their side lengths.

[0018] Preferably, the thermally conductive filler comprises the following components calculated by mass: 16.5 to 21.5 parts of nano boron nitride and 16.5 to 21.5 parts of fumed silica.

[0019] Preferably, the mass fraction of the flame retardant is 21.5 to 26.5 parts.

[0020] More preferably, the flame retardant includes the following components calculated by mass: 9.5-12.5 parts of nano magnesium hydroxide, 5.5-8.5 parts of ammonium polyphosphate, and 4.5-8.5 parts of melamine cyanurate.

[0021] By controlling the mass proportion of each component in the flame retardant and thermal conductive filler within the above range, the components can better exert their synergistic effects and obtain silicone rubber with better performance in all aspects.

[0022] Preferably, the cross-linking agent comprises hydrogen-containing silicone oil.

[0023] More preferably, the hydrogen content of the hydrogen-containing silicone oil is 0.25-1.5%.

[0024] When vinyl-terminated polydimethylsiloxane (PDMS) is mixed with a small amount of hydrogenated silicone oil in a specific ratio as the base polymer, PDMS can provide good flexibility and basic physical properties, while hydrogenated silicone oil participates in the subsequent curing reaction, strengthens the cross-linking network, and improves the overall performance of the material. Compared with traditional silicone rubber, which only uses a single polydimethylsiloxane (PDMS) as the base polymer, the cross-linking network is relatively simple and the overall performance improvement is limited.

[0025] Preferably, the catalyst comprises a platinum catalyst.

[0026] Preferably, the inhibitor comprises a vinyl ring.

[0027] More preferably, the raw materials for preparing the high-performance silicone rubber further include at least one of a dispersant and a lubricant; the dispersant includes γ-aminopropyltriethoxysilane, and the lubricant includes polydimethylsiloxane.

[0028] More preferably, the mass fraction of the dispersant is 0.5 to 1 part.

[0029] More preferably, the mass fraction of the lubricant is 1 to 2 parts.

[0030] The present invention also protects a method for preparing high-performance silicone rubber, comprising the following steps:

[0031] The prepared raw materials are mixed and vacuum degassed, and then cured at a temperature above 120° C., and high-performance silicone rubber can be obtained after curing.

[0032] In a specific embodiment of the present invention, the mixing of the raw materials is as follows: adding the raw materials into a high-speed mixer, and mixing at a rotation speed of 35 rpm for 25 to 60 minutes at room temperature.

[0033] In a specific embodiment of the present invention, the vacuum degassing is: degassing for 1 to 2.5 hours at a vacuum degree of -0.08 MPa to -0.1 MPa. The purpose of vacuum degassing is to remove bubbles in the raw materials after mixing.

[0034] In a specific embodiment of the present invention, the curing time is no longer than 60 minutes.

[0035] The present invention also protects the application of the high-performance silicone rubber in sealing materials.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The tensile strength of the silicone rubber provided by the present invention is greater than 4MPa, the elongation at break is more than 180%, the thermal conductivity is as low as 1.5W / m·k, and the volume resistivity is as high as 1.0×10 12 Ω·cm, dielectric strength>20kV / mm, flame retardant grade reaches UL-V0, thermal conductivity, insulation, flame retardancy and mechanical properties are excellent, with broad application prospects, suitable for the preparation of electronic appliances, automotive industry, aerospace and construction and other fields of sealing materials. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents. Among them, the raw material information used in each embodiment and comparative example is as follows:

[0039] Fumed silica A1: Specific surface area 150m 2 / g, produced by Cabot Corporation.

[0040] Fumed silica A2: Specific surface area 130m 2 / g, produced by Cabot Corporation.

[0041] Fumed silica A3: Specific surface area 180m 2 / g, produced by Cabot Corporation.

[0042] Fumed silica A4: Specific surface area 170m 2 / g, produced by Cabot Corporation.

[0043] Nano magnesium hydroxide B1: average lateral dimension length is 50±5nm, thickness is ~30nm, produced by Shandong Hailong Magnesium Industry Co., Ltd.

[0044] Nano magnesium hydroxide B2: The average lateral dimension length is 35±5nm, the thickness is ~30nm, produced by Shandong Hailong Magnesium Industry Co., Ltd.

[0045] Nano magnesium hydroxide B3: average lateral size is 80±5nm, thickness is ~30nm, produced by Shandong Hailong Magnesium Industry Co., Ltd.

[0046] Nano magnesium hydroxide B4: average lateral size is 65±5nm, thickness is ~30nm, produced by Shandong Hailong Magnesium Industry Co., Ltd.

[0047] Nano boron nitride C1: average lateral size is 65±5nm, thickness is ~30nm, produced by Hefei AVIC Nanotechnology Co., Ltd.

[0048] Nano boron nitride C2: average lateral size is 50±5nm, thickness is ~30nm, produced by Hefei AVIC Nanotechnology Co., Ltd.

[0049] Nano boron nitride C3: average lateral size is 90±5nm, thickness is ~30nm, produced by Hefei AVIC Nanotechnology Co., Ltd.

[0050] Nano boron nitride C4: average lateral size is 80±5nm, thickness is ~30nm, produced by Hefei AVIC Nanotechnology Co., Ltd.

[0051] Alumina whiskers: length: 10-50μm, diameter: 0.1-10μm, produced by Guangdong Baisang Polymer Materials Co., Ltd.

[0052] Vinyl-terminated polydimethylsiloxane: purchased from Dow Corning, USA.

[0053] Hydrogen-containing silicone oil: hydrogen content 0.82%, purchased from Dow Corning, USA.

[0054] Example 1

[0055] A high-performance silicone rubber, comprising the following raw materials calculated by weight:

[0056] 100 parts of vinyl-terminated polydimethylsiloxane, 11.6 parts of hydrogenated silicone oil, 38 parts of thermal conductive filler, 23.5 parts of flame retardant, 0.35 parts of platinum catalyst, 1.13 parts of vinyl ring body, 0.75 parts of dispersant γ-aminopropyl triethoxysilane, 1.5 parts of lubricant polydimethylsiloxane;

[0057] The thermal conductive filler includes 19 parts of nano boron nitride C1 and 19 parts of fumed silica A1;

[0058] The flame retardant includes 10 parts of nano magnesium hydroxide B1, 6.4 parts of ammonium polyphosphate and 7.1 parts of melamine cyanurate.

[0059] The preparation method of the high-performance silicone rubber in this embodiment comprises the following steps:

[0060] Add the prepared raw materials into a high-speed mixer and mix them at a speed of 35 rpm for 45 minutes at room temperature; degas for 1.5 hours at a vacuum degree of -0.09 MPa, and then cure at 125°C for 45 minutes to obtain high-performance silicone rubber.

[0061] Example 2

[0062] A high-performance silicone rubber, which is different from Example 1 only in that:

[0063] The thermal conductive filler includes 16.5 parts of nano boron nitride C1 and 21.5 parts of fumed silica A1.

[0064] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0065] Example 3

[0066] A high-performance silicone rubber, which is different from Example 1 only in that:

[0067] The thermal conductive filler includes 16.5 parts of fumed silica A1 and 21.5 parts of nano boron nitride C1.

[0068] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0069] Example 4

[0070] A high-performance silicone rubber, which is different from Example 1 only in that:

[0071] The mass fraction of the flame retardant is 21.5 parts, including 9.5 parts of nano magnesium hydroxide B1, 8.5 parts of ammonium polyphosphate and 3.5 parts of melamine cyanurate.

[0072] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0073] Example 5

[0074] A high-performance silicone rubber, which is different from Example 1 only in that:

[0075] The mass fraction of the flame retardant is 26.5 parts, including 12.5 parts of nano magnesium hydroxide B1, 5.5 parts of ammonium polyphosphate and 8.5 parts of melamine cyanurate.

[0076] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0077] Example 6

[0078] A high-performance silicone rubber, which is different from Example 1 only in that:

[0079] The thermal conductive filler includes 25 parts of nano boron nitride C1 and 15 parts of fumed silica A1.

[0080] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0081] Example 7

[0082] A high-performance silicone rubber, which is different from Example 1 only in that:

[0083] The thermal conductive filler includes 15 parts of nano boron nitride C1 and 25 parts of fumed silica A1.

[0084] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0085] Example 8

[0086] A high-performance silicone rubber, which is different from Example 1 only in that:

[0087] The mass fraction of the flame retardant is 21.5 parts, including 13 parts of nano magnesium hydroxide B1, 3.5 parts of ammonium polyphosphate and 5 parts of melamine cyanurate.

[0088] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0089] Example 9

[0090] A high-performance silicone rubber, which is different from Example 1 only in that:

[0091] The mass fraction of the flame retardant is 21.5 parts, including 6 parts of nano magnesium hydroxide B1, 8.5 parts of ammonium polyphosphate and 7 parts of melamine cyanurate.

[0092] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0093] Example 10

[0094] A high-performance silicone rubber, which is different from Example 1 only in that:

[0095] The fumed silica A1 in the thermal conductive filler was replaced with fumed silica A4.

[0096] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0097] Embodiment 11

[0098] A high-performance silicone rubber, which is different from Example 1 only in that:

[0099] The nano magnesium hydroxide B1 in the flame retardant is replaced by nano magnesium hydroxide B4.

[0100] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0101] Example 12

[0102] A high-performance silicone rubber, which is different from Example 1 only in that:

[0103] The nano boron nitride in the thermal conductive filler is replaced by C1 or nano boron nitride C4.

[0104] The preparation method of the high performance silicone rubber in this embodiment is consistent with that in Embodiment 1.

[0105] Comparative Example 1

[0106] A silicone rubber, wherein the difference from Example 1 is only that:

[0107] The mass fraction of the thermally conductive filler is 38 parts, which only contains fumed silica A1.

[0108] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0109] Comparative Example 2

[0110] A silicone rubber, wherein the difference from Example 1 is only that:

[0111] The mass fraction of the thermal conductive filler is 38 parts, which only contains nano boron nitride C1.

[0112] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0113] Comparative Example 3

[0114] A silicone rubber, wherein the difference from Example 1 is only that:

[0115] The mass fraction of the flame retardant is 21.5 parts, which only contains 9.5 parts of nano magnesium hydroxide B1 and 12 parts of ammonium polyphosphate.

[0116] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0117] Comparative Example 4

[0118] A silicone rubber, wherein the difference from Example 1 is only that:

[0119] The mass fraction of the flame retardant is 21.5 parts, which only contains 9.5 parts of nano magnesium hydroxide B1 and 12 parts of melamine cyanurate.

[0120] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0121] Comparative Example 5

[0122] A silicone rubber, wherein the difference from Example 1 is only that:

[0123] The mass fraction of the flame retardant is 21.5 parts, which only contains 8.5 parts of ammonium polyphosphate and 13 parts of melamine cyanuric acid.

[0124] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0125] Comparative Example 6

[0126] A silicone rubber, wherein the difference from Example 1 is only that:

[0127] The fumed silica in the thermal conductive filler was replaced with alumina of the same particle size.

[0128] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0129] Comparative Example 7

[0130] A silicone rubber, wherein the difference from Example 1 is only that:

[0131] The nano boron nitride in the thermal conductive filler is replaced by flake aluminum oxide of the same size.

[0132] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0133] Comparative Example 8

[0134] A silicone rubber, wherein the difference from Example 1 is only that:

[0135] The fumed silica in the thermally conductive filler was replaced with alumina whiskers.

[0136] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0137] Comparative Example 9

[0138] A silicone rubber, wherein the difference from Example 1 is only that:

[0139] The nano boron nitride in the thermal conductive filler is replaced by aluminum oxide whiskers.

[0140] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0141] Comparative Example 10

[0142] A silicone rubber, wherein the difference from Example 1 is only that:

[0143] The nano boron nitride in the thermal conductive filler is replaced by C1 or nano boron nitride C2.

[0144] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0145] Comparative Example 11

[0146] A silicone rubber, wherein the difference from Example 1 is only that:

[0147] The nano boron nitride in the thermal conductive filler is replaced by C1 or nano boron nitride C3.

[0148] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0149] Comparative Example 12

[0150] A silicone rubber, wherein the difference from Example 1 is only that:

[0151] The fumed silica A1 in the thermal conductive filler was replaced with fumed silica A2.

[0152] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0153] Comparative Example 13

[0154] A silicone rubber, wherein the difference from Example 1 is only that:

[0155] The fumed silica A1 in the thermal conductive filler was replaced with fumed silica A3.

[0156] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0157] Comparative Example 14

[0158] A silicone rubber, wherein the difference from Example 1 is only that:

[0159] The nano magnesium hydroxide B1 in the flame retardant is replaced by nano magnesium hydroxide B2.

[0160] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0161] Comparative Example 15

[0162] A silicone rubber, wherein the difference from Example 1 is only that:

[0163] The nano magnesium hydroxide B1 in the flame retardant is replaced by nano magnesium hydroxide B3.

[0164] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0165] Comparative Example 16

[0166] A silicone rubber, wherein the difference from Example 1 is only that:

[0167] The nano magnesium hydroxide B1 in the flame retardant was replaced with aluminum hydroxide of the same size.

[0168] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0169] Comparative Example 17

[0170] A silicone rubber, wherein the difference from Example 1 is only that:

[0171] The nano magnesium hydroxide B1 in the flame retardant was replaced with titanium oxide of the same size.

[0172] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0173] Comparative Example 18

[0174] A silicone rubber, wherein the difference from Example 1 is only that:

[0175] The ammonium polyphosphate in the flame retardant was replaced by tricresyl phosphate (TCP).

[0176] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0177] Comparative Example 19

[0178] A silicone rubber, wherein the difference from Example 1 is only that:

[0179] The melamine cyanurate in the flame retardant was replaced by tricresyl phosphate (TCP).

[0180] The preparation method of the silicone rubber in this comparative example is consistent with that in Example 1.

[0181] Performance Testing

[0182] Tensile strength test: Tested in accordance with GB / T 528-2009.

[0183] Elongation at break test: Tested in accordance with GB / T 528-2009.

[0184] Thermal conductivity test: Tested in accordance with GB / T 10295-2008.

[0185] Volume resistivity test: Tested in accordance with GB / T 2439-2001.

[0186] Dielectric strength test: Tested in accordance with GB / T 1695-2005.

[0187] Flame retardant grade test: Tested in accordance with GB / T 10707-2008.

[0188] The specific performance test data is shown in Table 1 below:

[0189] Table 1. Various performance data of silicone rubber obtained in Examples and Comparative Examples

[0190]

[0191]

[0192]

[0193] According to the data in Table 1 above, the tensile strength of the silicone rubber provided by the present invention is greater than 4 MPa, the elongation at break is more than 180%, the thermal conductivity is as low as 1.45 W / m·k, and the volume resistivity is as high as 1.0×10 12 Ω·cm, dielectric strength>20kV / mm, flame retardant grade reaches UL-V0, thermal conductivity, insulation, flame retardancy and mechanical properties are excellent, with broad application prospects, suitable for the preparation of electronic appliances, automotive industry, aerospace and construction and other fields of sealing materials.

[0194] From the data of Examples 1 to 3 and 6 to 7 in Table 1 above, it can be seen that when the mass fractions of nano boron nitride and fumed silica included in the thermally conductive filler are respectively within the preferred range of 16.5 to 21.5 parts (Examples 1 to 3) of the present invention, the comprehensive performance of the obtained thermally conductive silicone rubber is better, indicating that the above mass fractions of the two thermally conductive fillers are compounded with additives such as flame retardants to obtain better synergistic effects.

[0195] From the data of Examples 1, 4-5, 8-9 in Table 1 above, it can be seen that when the mass fractions of the three components in the flame retardant are 9.5-12.5 parts of the preferred nano-magnesium hydroxide of the present invention, 5.5-8.5 parts of ammonium polyphosphate, and 4.5-8.5 parts of melamine cyanurate (Examples 1, 4-5), the comprehensive performance of the obtained silicone rubber is also better, indicating that the three can obtain better synergistic effect within a certain addition amount.

[0196] According to Examples 10 to 12 and Comparative Examples 10 to 15, if the size of any component in the flame retardant or the thermally conductive filler is inappropriate, the synergistic effect between the thermally conductive filler and the flame retardant will decrease, and the comprehensive performance of the obtained silicone rubber will decrease accordingly.

[0197] According to Comparative Examples 1 to 2, when the thermally conductive filler contains only any one of fumed silica or nano boron nitride, it is difficult to form a rich and coherent thermal conductive path. Although the obtained silicone rubber has excellent mechanical, insulating and flame retardant properties, its thermal conductivity is insufficient and its comprehensive performance is not as good as the silicone rubber obtained in the embodiments of the present invention.

[0198] According to Comparative Examples 3 to 5, the mass fractions of the components in the flame retardant are not appropriate. Although the flame retardant can still help improve the integrity of the thermal conduction path and promote the generation of fine crystal strengthening, the flame retardant performance of the silicone rubber is insufficient.

[0199] According to Comparative Examples 6 to 9 and Comparative Examples 16 to 19, when any component in the thermal conductive filler and the flame retardant of the present invention is replaced with a component of similar properties, the comprehensive performance of the obtained silicone rubber will decrease. It is speculated that this is because the specific components selected by the present invention have better compatibility and can fully exert the synergistic effect after compounding.

[0200] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A high performance silicone rubber, characterized in that: Including the following preparation raw materials calculated by mass: 100 parts of vinyl-terminated polydimethylsiloxane, 8-14 parts of cross-linking agent, 33-43 parts of thermal conductive filler, 19.5-27.5 parts of flame retardant, 0.2-0.4 parts of catalyst, 0.8-1.3 parts of inhibitor; The thermal conductive filler comprises nano boron nitride and fumed silica; The flame retardant includes nano magnesium hydroxide, ammonium polyphosphate and melamine cyanurate; The average lateral size of the nano boron nitride is 60 to 80 nm; The specific surface area of ​​the fumed silica is 140 to 170 m 2 / g; The average lateral size of the nano magnesium hydroxide is 40-65 nm.

2. The high performance silicone rubber according to claim 1, characterized in that: The thermal conductive filler comprises the following components calculated by mass: 16.5 to 21.5 parts of nano boron nitride and 16.5 to 21.5 parts of fumed silica.

3. The high performance silicone rubber according to claim 1, characterized in that: The flame retardant comprises the following components calculated by mass: 9.5-12.5 parts of nano magnesium hydroxide, 5.5-8.5 parts of ammonium polyphosphate, and 3.5-8.5 parts of melamine cyanurate.

4. The high performance silicone rubber according to claim 1, characterized in that: The crosslinking agent includes hydrogen-containing silicone oil.

5. The high performance silicone rubber according to claim 4, characterized in that: The hydrogen content of the hydrogen-containing silicone oil is 0.25-1.5%.

6. The high performance silicone rubber according to claim 1, characterized in that: The catalyst includes a platinum catalyst.

7. The high performance silicone rubber according to claim 1, characterized in that: The inhibitor includes a vinyl ring.

8. The high performance silicone rubber according to claim 1, characterized in that: It also includes at least one of a dispersant and a lubricant; the dispersant includes γ-aminopropyltriethoxysilane, and the lubricant includes polydimethylsiloxane.

9. The method for preparing the high-performance silicone rubber according to any one of claims 1 to 7, characterized in that: The steps include: The prepared raw materials are mixed and vacuum degassed, and then cured at a temperature above 120° C., and high-performance silicone rubber can be obtained after curing.

10. Use of the high-performance silicone rubber according to any one of claims 1 to 7 in sealing materials.

Images