Heat-conducting wave-absorbing gasket as well as preparation method and application thereof

Abstract

The invention relates to a heat-conducting and wave-absorbing gasket and a preparation method and application thereof, and belongs to the technical field of heat-conducting and wave-absorbing composite materials. The preparation method of the heat-conducting wave-absorbing gasket comprises the following steps: performing vacuum heating, stirring and mixing on vinyl silicone oil and methyl vinyl raw rubber to obtain an organic silicon resin matrix, dividing the organic silicon resin matrix into two parts, adding a curing agent into one part to obtain a component A sizing material, and adding an inhibitor and a catalyst into the other part to obtain a component B sizing material; carrying out coating modification treatment on the heat-conducting filler and the wave-absorbing filler by adopting a silane coupling agent to obtain a mixed modified filler; and mixing the component A sizing material, the component B sizing material and the mixed modified filler, performing compression molding, and performing heating curing to obtain the heat-conducting wave-absorbing gasket. The heat-conducting and wave-absorbing gasket has the characteristics of high resilience, low volatility and low oil diffusion while having the characteristics of high heat conductivity and wave absorption, can be effectively applied to electronic components, and is particularly suitable for being applied to airtight security and optical module components.

Description

Technical Field

[0001] The present application relates to the technical field of heat-conducting and wave-absorbing composite materials, and in particular to a heat-conducting and wave-absorbing gasket and a preparation method and application thereof. Background Art

[0002] With the continuous evolution of communication technology, new generation electronic components such as RFFE / antenna modules for 5G communication, WiFi6, radar modules, and optical modules for optical communication have demonstrated ultra-high power density and transmission frequency bands. However, these high performances are also accompanied by a large amount of heat and electromagnetic radiation interference generated by electronic components during operation, which undoubtedly puts more stringent requirements on the thermal management and electromagnetic shielding technology of the product.

[0003] As a key component in the field of thermal management, thermal pads can effectively export the heat generated inside electronic components to ensure the stable operation of the product. However, the problems faced by thermal pads during use cannot be ignored. For example, small molecules and free silicone oil inside thermal pads will gradually precipitate during long-term use. In particular, thermal pads are used inside sealed components such as security and optical modules. These precipitated small molecules and silicone oil are easily gathered on the surface of transparent materials such as glass, causing lens blur and light path obstruction, which in turn affects the performance of the entire system. In addition, thermal conductive products with poor or no resilience will have gaps between heating components and radiators after long-term use. These gaps will not only reduce the heat conduction efficiency, but may also cause the temperature of the heating element to be too high, thereby shortening its service life. How to solve the problem of precipitation of small molecules and silicone oil inside thermal pads while ensuring thermal conductivity, improve the resilience of thermal conductive products, and solve the problem of electromagnetic radiation interference in a limited space has become a problem that needs to be solved urgently. Summary of the invention

[0004] To solve the above problems, the purpose of the embodiments of the present application includes providing a thermally conductive and absorbing gasket and a preparation method and application thereof. The prepared thermally conductive and absorbing gasket has high thermal conductivity and wave absorbing properties while having high resilience, low volatility and low oil diffusion properties.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a thermally conductive wave-absorbing gasket, comprising the following steps:

[0006] Pretreatment of organic silicone resin: vinyl silicone oil and methyl vinyl raw rubber are heated and stirred in a vacuum to obtain an organic silicone resin matrix, and the organic silicone resin matrix is ​​divided into two parts, a curing agent is added to one part to obtain a component A rubber material, and an inhibitor and a catalyst are added to the other part to obtain a component B rubber material;

[0007] Powder surface modification: Use silane coupling agent to coat and modify the thermal conductive filler and the wave absorbing filler to obtain a mixed modified filler;

[0008] Forming of heat-conducting and wave-absorbing gasket: Mix the rubber material of component A, the rubber material of component B and the mixed modified filler, press and form, heat and cure, and obtain the heat-conducting and wave-absorbing gasket.

[0009] In the above technical scheme, by mixing methyl vinyl rubber and vinyl silicone oil as the base resin, combining vacuum heating pretreatment and powder mixing surface modification synergistically, the prepared thermal conductive wave-absorbing gasket has high thermal conductivity, wave-absorbing properties, high resilience, low volatility and low oil diffusion properties. Among them, the use of vinyl silicone oil and methyl vinyl rubber as the base resin can effectively improve the resilience of the product, balance the filling and strength, and combined with vacuum heating pretreatment, it can effectively remove small siloxane molecules and reduce volatility and oil penetration. Mixing and modifying the thermal conductive filler and the wave-absorbing filler can increase the mixing uniformity of the two. After modification, it can enhance the combination with the silicone resin and increase the filling amount and filling uniformity in the resin system.

[0010] In some embodiments of the present application, the weight average molecular weight of the methyl vinyl rubber is 500,000 to 700,000.

[0011] In the above technical solution, the weight average molecular weight of methyl vinyl rubber is within an appropriate range, which can provide elasticity, and the molecular chain length can lock the small molecular branched silicone oil, and the methyl vinyl rubber and vinyl silicone oil have good compatibility. The combination of the two can ensure strength, improve resilience, and reduce oil diffusion. In addition, the viscosity of the mixed resin can be effectively controlled, which is conducive to the subsequent uniform filling of powder.

[0012] In some embodiments of the present application, in the silicone resin pretreatment step, the vacuum heating conditions include: continuous stirring at 80-150° C. for 1-2 hours.

[0013] In the above technical solution, continuous stirring at high temperature can better disperse the methyl vinyl rubber and the vinyl silicone oil, while removing small siloxane molecules.

[0014] In some embodiments of the present application, the powder surface modification treatment step includes:

[0015] The wave absorbing filler and the thermal conductive filler with different particle sizes are stirred and mixed to obtain a mixed filler;

[0016] Mixing and diluting the silane coupling agent with ethanol to obtain a modified solution;

[0017] Under heating and stirring conditions, the modified solution is sprayed onto the surface of the mixed filler to obtain a mixed modified filler.

[0018] Optionally, the heating and stirring temperature is 80-100° C., and the time is 0.5-1 h.

[0019] In the above technical solution, spraying the modified solution under heating and stirring conditions can achieve surface coating modification more uniformly and fully.

[0020] In some embodiments of the present application, the thermal conductive filler includes at least one of aluminum oxide, aluminum nitride or diamond, and the particle size of the thermal conductive filler is 0.1 to 120 μm. The wave absorbing filler includes at least one of carbonyl iron powder, aluminum silicon powder, tin oxide powder or tin pyrophosphate powder; and the silane coupling agent is a vinyl modified silane coupling agent.

[0021] In the above technical solution, a vinyl-modified silane coupling agent is used for surface coating modification, and vinyl groups are chemically grafted on the surface of the filler, which can increase the compatibility with the silicone resin and reduce the interface thermal resistance.

[0022] In some embodiments of the present application, based on the total weight of the thermally conductive and absorbing gasket, the weight percentages of the components in the silicone resin pretreatment step are respectively:

[0023] 55-105 parts of vinyl silicone oil of different viscosities, 20-30 parts of methyl vinyl rubber, 3-8 parts of curing agent, 0.05-0.2 parts of inhibitor, and 1-3 parts of catalyst.

[0024] Optionally, the vinyl silicone oil includes 15 to 35 parts of vinyl silicone oil with a viscosity of 100 to 200 mPa.s, 15 to 35 parts of vinyl silicone oil with a viscosity of 400 to 600 mPa.s, and 15 to 25 parts of vinyl silicone oil with a viscosity of 8000 to 10000 mPa.s.

[0025] In the above technical solution, different viscosities correspond to different weight-average molecular weights and different molecular chain lengths. By matching different viscosities, the uniformity of powder filling can be improved, while balancing strength and resilience.

[0026] In some embodiments of the present application, based on the total weight of the thermally conductive and absorbing gasket, the weight proportions of each component in the powder surface modification step are: 1000-1500 parts of thermally conductive fillers of different particle sizes and 400-600 parts of absorbing fillers.

[0027] Optionally, the thermal conductive filler includes 700-900 parts of spherical alumina with a particle size of 90-120 μm, 50-200 parts of spherical alumina with a particle size of 10-20 μm, 50-90 parts of quasi-spherical alumina with a particle size of 0.5-2 μm, and 100-230 parts of spherical aluminum nitride with a particle size of 30-50 μm.

[0028] In the above technical solution, large-particle powder has better thermal conductivity, but more voids, and small-particle powder has a small stacking porosity, but a large oil absorption value and less filling. By matching thermal conductive fillers of different particle sizes, a better network structure and a better thermal conductivity path can be formed, and the voids existing in the stacking of a single particle size can be reduced, thereby improving thermal conductivity and filling characteristics.

[0029] In some embodiments of the present application, in the step of forming the thermal conductive and absorbing gasket, the mixing method includes:

[0030] Mixing part of the mixed modified filler with the rubber material of component A to obtain a mixed rubber material of component A;

[0031] Mixing another portion of the mixed modified filler with the rubber material of component B to obtain a mixed rubber material of component B;

[0032] Mix the mixed rubber material of component A and the mixed rubber material of component B, and stir them in a water-cooled vacuum at a temperature below 30°C for 30 to 180 minutes.

[0033] In the above technical solution, the mixed modified filler is mixed with the mixed rubber materials of components A and B in steps, and then stirred together in a water-cooled vacuum, which can effectively improve the filling uniformity of the powder in the resin.

[0034] In a second aspect, an embodiment of the present application provides a thermally conductive and absorbing gasket, which is prepared by the above-mentioned preparation method.

[0035] In a third aspect, an embodiment of the present application further provides an application of the above-mentioned thermally conductive and absorbing gasket in electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A process flow chart of a method for preparing a thermally conductive and wave-absorbing gasket provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] Figure 1 A process flow chart of a method for preparing a thermally conductive and wave-absorbing gasket provided in an embodiment of the present application.

[0039] See also Figure 1 The method for preparing the heat-conducting and wave-absorbing gasket provided in the embodiment of the present application comprises the following steps:

[0040] S110, pretreatment of the silicone resin matrix: heating the vinyl silicone oil and the methyl vinyl rubber under vacuum, stirring and mixing, to obtain the silicone resin matrix; dividing the silicone resin matrix into two parts, adding a curing agent to one part to obtain a component A rubber material, and adding an inhibitor and a catalyst to the other part to obtain a component B rubber material.

[0041] Among them, the weight average molecular weight of methyl vinyl rubber is large enough to provide elasticity, and the molecular chain length can lock the small molecular branched silicone oil and reduce oil diffusion. In addition, methyl vinyl rubber and vinyl silicone oil belong to the same category, have good compatibility, and complement each other. Volatilization and oil seepage are mainly caused by the presence of small siloxane molecules in the product, and a small amount of long-chain silicone oil that does not participate in the curing reaction. Vacuum heating can remove small siloxane molecules. Therefore, by mixing vinyl silicone oil and methyl vinyl rubber as the base resin and pre-treating it, the product's resilience, volatility and oil diffusion properties can be effectively improved.

[0042] The weight average molecular weight of the methyl vinyl rubber may be 500,000 to 700,000. For example, the weight average molecular weight of the methyl vinyl rubber may be 500,000, 600,000, or 700,000.

[0043] Based on the total weight of the thermally conductive wave-absorbing gasket, the amount of each component used in the pretreatment step of the organic silicone resin matrix can be: 55-105 parts of vinyl silicone oil of different viscosities, 20-30 parts of methyl vinyl rubber, 3-8 parts of curing agent, 0.05-0.2 parts of inhibitor, and 1-3 parts of catalyst. By controlling the proportion of each component, the filling property, strength and resilience can be effectively balanced.

[0044] The viscosity of the vinyl silicone oil may be 100 to 10,000 mPa.s. Specifically, the vinyl silicone oil may include: 15 to 35 parts of vinyl silicone oil with a viscosity of 100 to 200 mPa.s, 15 to 35 parts of vinyl silicone oil with a viscosity of 400 to 600 mPa.s, and 15 to 25 parts of vinyl silicone oil with a viscosity of 8,000 to 10,000 mPa.s.

[0045] The conditions for vacuum heating, stirring and mixing include: stirring continuously for 1 to 2 hours at 80 to 150° C. Preferably, stirring continuously for 2 hours at 150° C. under vacuum.

[0046] Optionally, the curing agent may be hydrogenated silicone oil, the inhibitor may be ethynyl cyclohexanol, and the catalyst may be a platinum water catalyst. The addition of the curing agent and the catalyst may promote the crosslinking reaction of the silicone resin, and facilitate the curing and molding of the silicone resin to prepare the desired product. During the curing process of the liquid resin, in order to allow sufficient operating time for the mixing of the raw materials, an inhibitor is also added to delay the crosslinking and curing of the liquid resin. The inhibitor can inhibit the crosslinking rate of the silicone resin at room temperature, leaving enough time for the mixing operation to ensure that all the raw materials are mixed evenly.

[0047] S120, powder surface modification: using silane coupling agent to modify the surface of thermal conductive filler and wave absorbing filler to obtain mixed modified filler.

[0048] The mixed modified filler includes modified thermal conductive filler and modified wave absorbing filler. Based on the total weight of the thermal conductive wave absorbing gasket, the usage of the thermal conductive filler and the wave absorbing filler can be: 1000-1500 parts of thermal conductive filler with different particle sizes and 400-600 parts of wave absorbing filler.

[0049] It can be understood that in the embodiment of the present application, the weight added after the silane coupling agent coating modification can be ignored. The weight of the modified thermal conductive filler can be regarded as equal to the weight of the thermal conductive filler, and the weight of the modified absorbing filler can be regarded as equal to the weight of the absorbing filler.

[0050] The thermal conductive filler may include at least one of aluminum oxide, aluminum nitride, diamond, and boron nitride, and the particle size may be 0.1 to 120 μm. Preferably, the thermal conductive filler may include: 700 to 900 parts of spherical aluminum oxide with a particle size of 90 to 120 μm, 50 to 200 parts of spherical aluminum oxide with a particle size of 10 to 20 μm, 50 to 90 parts of quasi-spherical aluminum oxide with a particle size of 0.5 to 2 μm, and 100 to 230 parts of spherical aluminum nitride with a particle size of 30 to 50 μm.

[0051] The absorbing filler may include at least one of spherical carbonyl iron powder, flaky iron silicon aluminum, snowflake-shaped tin oxide and tin pyrophosphate. Different types and particle sizes of absorbing fillers may be selected to broaden the absorption frequency band of the product for electromagnetic waves and improve the electromagnetic wave absorption capacity, thereby increasing the application range of the product.

[0052] The silane coupling agent may be a vinyl-modified silane coupling agent, for example, vinyltrimethoxysilane, vinyltriethoxysilane, or the like.

[0053] It is understandable that other coupling agents with reactive groups or other excellent grafting effects with a thermal decomposition temperature above 200° C. can also be used. The coupling agent has a high thermal decomposition temperature, has excellent stability at high temperatures after coating and modification, and can also reduce the impact of volatilization.

[0054] In the embodiment of the present application, the step of powder surface modification treatment may specifically include:

[0055] The wave absorbing filler and the thermal conductive filler with different particle sizes are stirred and mixed to obtain a mixed filler;

[0056] Mixing and diluting the silane coupling agent with ethanol to obtain a modified solution;

[0057] Under heating and stirring conditions, the modified solution is sprayed onto the surface of the mixed filler to obtain a mixed modified filler.

[0058] The mass ratio of the silane coupling agent to the ethanol may be 1:5, and the amount of the silane coupling agent may be 3.5 wt % of the total weight of the mixed powder.

[0059] The conditions for heating and stirring include: temperature of 80-100° C., time of 0.5-1 h, and stirring speed of 800 rpm / min.

[0060] S130, forming a heat-conducting wave-absorbing gasket: mixing the rubber material of component A, the rubber material of component B and the mixed modified filler, pressing and forming, heating and curing, and rolling and slicing to obtain a heat-conducting wave-absorbing gasket.

[0061] The mixing method may include: mixing part of the mixed modified filler with the rubber material of component A to obtain the mixed rubber material of component A. Mixing another part of the mixed modified filler with the rubber material of component B to obtain the mixed rubber material of component B. Mixing the mixed rubber material of component A and the mixed rubber material of component B, and stirring them in a water-cooled vacuum at a temperature below 30° C. for 30 to 180 minutes. Mixing at a low temperature in a vacuum can inhibit the cross-linking reaction and ensure uniform mixing.

[0062] The conditions for heat curing may include: a temperature of 80 to 120° C. and a time of 15 to 30 minutes.

[0063] The rubber obtained after mixing is in a colloid state at room temperature, and can be used to prepare a wave-absorbing thermally conductive gasket of a specified thickness and size by pressing and molding. Before pressing and molding, vacuum treatment is performed to extract the air mixed in the colloid, thereby avoiding the presence of bubbles in the pressed thermally conductive wave-absorbing gasket, which affects the strength and thermal conductivity. After pressing and molding, heating is used to promote the reaction between the curing agent and the resin, improve the catalytic efficiency of the catalyst, and reduce the inhibitory effect of the inhibitor on the cross-linking reaction, thereby accelerating the cross-linking and curing of the silicone resin, so that the prepared thermally conductive wave-absorbing gasket reaches a certain strength and hardness.

[0064] The preparation method of the thermally conductive absorbing gasket provided in the embodiment of the present application first undergoes precise pretreatment and mixing to ensure the basic stability of the resin system and the optimization of the elastic modulus, and also lays a good foundation for the subsequent filler modification through intermolecular interactions. The thermally conductive filler and the absorbing filler are cleverly introduced and mixed and modified to achieve the fine dispersion of the filler and the close combination of the resin matrix. The addition of the thermally conductive filler not only significantly improves the thermal conductivity efficiency of the material and forms an efficient heat transfer network, but also effectively suppresses the thermal expansion of the resin matrix at high temperatures through its unique microstructure, further enhancing the dimensional stability and durability of the material. At the same time, this structural optimization also promotes the stability of the volatile components inside the resin and reduces the volatility of the overall thermally conductive gasket. The introduction of absorbing fillers gives the material a unique electromagnetic wave absorption ability. These fillers convert incident electromagnetic waves into other forms of energy dissipation through specific physical or chemical mechanisms, such as electromagnetic resonance, scattering or energy conversion, thereby reducing the reflection and transmission of electromagnetic waves. It is worth noting that this wave absorption process and the heat conduction process form a synergistic effect to a certain extent: part of the absorbed electromagnetic wave energy is converted into thermal energy and quickly dispersed through the thermal conduction network, avoiding local overheating and further improving the thermal management capabilities and safety of the material.

[0065] The embodiment of the present application also provides a heat-conducting and wave-absorbing gasket prepared by the above-mentioned preparation method and its application in electronic components.

[0066] Among them, electronic components may include RFFE / antenna modules for 5G communications, WiFi 6, radar modules, and optical modules for optical communications.

[0067] The thermally conductive wave-absorbing gasket has high thermal conductivity and wave-absorbing performance, as well as high resilience, low volatility, and low oil diffusion. When applied to electronic components, it can effectively improve the heat dissipation and electromagnetic interference problems caused by the high integration of electronic devices. In addition, it can solve the problem of poor contact caused by poor resilience of conventional products after long assembly compression time. It can be especially applied in the closed optical module industry to avoid the problem of siloxane precipitation pollution.

[0068] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0069] The sources of some of the raw materials used in the examples and comparative examples of the present application are shown in Table 1 below.

[0070] Table 1 Sources of some raw materials in the examples and comparative examples

[0071]

[0072] Example 1

[0073] This embodiment provides a heat-conducting and wave-absorbing gasket, and a preparation method thereof comprises the following steps:

[0074] (1) Pretreatment of organic silicone resin matrix: 15g of vinyl silicone oil with a viscosity of 100mPa.s, 35g of vinyl silicone oil with a viscosity of 500mPa.s, 15g of vinyl silicone oil with a viscosity of 10,000mPa.s and 28g of methyl vinyl rubber with a weight average molecular weight of 500,000 are centrifugally stirred at high temperature until the solid methyl vinyl rubber is completely compatible and dispersed evenly with the vinyl silicone oil, and then treated in a continuous heating 150°C, circulating stirring and vacuuming equipment for 2h to remove the siloxane small molecules in the synthesis process, and then cooled to obtain an organic silicone resin matrix. The treated organic silicone resin matrix is ​​divided into two parts, 4.5g of curing agent hydrogenated silicone oil is added to one part to obtain component A rubber, and 0.08g of ethynyl cyclohexanol inhibitor and 1.5g of platinum water catalyst are added to the other part to obtain component B rubber.

[0075] (2) Powder surface modification treatment: 750g of spherical alumina with a particle size of 120μm, 200g of spherical alumina with a particle size of 10μm, 55g of quasi-spherical alumina with a particle size of 0.6μm, 150g of spherical aluminum nitride powder with a particle size of 30μm, and 500g of spherical carbonyl iron powder were placed in a reactor. Vinyl-modified silane coupling agent was diluted to 50% with alcohol and coated on the surface of the powder by spraying. During the spraying process, the mixture was stirred and dispersed, and the temperature of the reactor was maintained at 80°C to allow the powder to fully react with the treatment. The treatment time was 1h to obtain a mixed modified filler.

[0076] (3) Forming of thermal conductive wave-absorbing gaskets: Mix part of the mixed modified filler with the rubber material of component A to obtain the mixed rubber material of component A. Mix the other part of the mixed modified filler with the rubber material of component B to obtain the mixed rubber material of component B. Place the mixed rubber material of component A and the mixed rubber material of component B in a stirring kettle and stir and mix them. During the stirring process, pass cooling water to ensure that the temperature of the stirring kettle is below 30°C. Continue vacuum stirring for 1 hour to obtain the final rubber material. Press the mixed rubber material on a calender and heat and cure it at a temperature of 100-120°C for 30 minutes in a tunnel furnace with a heating device. Roll and slice it to obtain a thermal conductive wave-absorbing gasket.

[0077] Example 2

[0078] This embodiment provides a heat-conducting and wave-absorbing gasket, and its preparation method is substantially the same as the preparation method in Embodiment 1, except that:

[0079] In step (1), the mixture is treated in a vacuum equipment with circulating stirring at 80° C. for 1 h.

[0080] The preparation methods of Examples 3-7 are substantially the same as those of Example 1, except that the amounts of the specific components are different, as shown in Table 2.

[0081] Table 2 Amount of raw materials used in Examples 1 to 7 (unit: g)

[0082]

[0083] Comparative Example 1

[0084] This comparative example provides a heat-conductive absorbing gasket, and its preparation method is roughly the same as the preparation method in Example 1, except that: in step (1), no methyl vinyl rubber is added, and no vacuum heating treatment is performed; in step (2), the absorbing filler and the heat-conductive filler are not mixed and surface modified.

[0085] The specific steps include:

[0086] (1) 25 g of vinyl silicone oil with a viscosity of 100 mPa.s, 45 g of vinyl silicone oil with a viscosity of 500 mPa.s and 23 g of vinyl silicone oil with a viscosity of 10,000 mPa.s were stirred and mixed at room temperature to obtain a silicone resin matrix, and the silicone resin matrix was divided into two parts, 4.5 g of curing agent hydrogenated silicone oil was added to one part to obtain component A rubber material, and 0.08 g of ethynyl cyclohexanol inhibitor and 1.5 g of platinum water catalyst were added to the other part to obtain component B rubber material.

[0087] (2) 750 g of spherical alumina with a particle size of 120 μm, 200 g of spherical alumina with a particle size of 10 μm, 55 g of quasi-spherical alumina with a particle size of 0.6 μm, 150 g of spherical aluminum nitride powder with a particle size of 30 μm, and 500 g of spherical carbonyl iron powder were placed in a reactor and mixed at 80°C for 1 hour.

[0088] (3) Forming of thermal conductive wave-absorbing gaskets: Mix part of the mixed modified filler with the rubber material of component A to obtain the mixed rubber material of component A. Mix the other part of the mixed modified filler with the rubber material of component B to obtain the mixed rubber material of component B. Stir and mix the mixed rubber materials of component A and component B, and pass cooling water during the stirring process to ensure that the temperature of the stirring kettle is below 30°C. Continue vacuum stirring for 1 hour to obtain the final rubber material. Press the mixed rubber material into shape on a calender, bake it in a tunnel furnace with a heating device, and roll and slice it after curing to obtain a thermal conductive wave-absorbing gasket.

[0089] Comparative Example 2

[0090] This comparative example provides a heat-conducting and wave-absorbing gasket, and its preparation method is substantially the same as the preparation method in Example 1, except that: methyl vinyl rubber is not added in step (1).

[0091] Step (1) specifically includes:

[0092] 25 g of vinyl silicone oil with a viscosity of 100 mPa.s, 45 g of vinyl silicone oil with a viscosity of 500 mPa.s and 23 g of vinyl silicone oil with a viscosity of 10,000 mPa.s were mixed in a continuous heating at 150°C, circulating stirring and vacuuming equipment for 2 h, and allowed to cool to obtain a silicone resin matrix. The silicone resin matrix was divided into two parts, 4.5 g of curing agent hydrogenated silicone oil was added to one part to obtain component A rubber, and 0.08 g of ethynyl cyclohexanol inhibitor and 1.5 g of platinum water catalyst were added to the other part to obtain component B rubber.

[0093] Comparative Example 3

[0094] This comparative example provides a heat-conducting wave-absorbing gasket, and its preparation method is substantially the same as the preparation method in Example 1, except that: in step (1), no vacuum heating and stirring treatment is performed.

[0095] Step (1) specifically includes:

[0096] 15 g of vinyl silicone oil with a viscosity of 100 mPa.s, 35 g of vinyl silicone oil with a viscosity of 500 mPa.s, 15 g of vinyl silicone oil with a viscosity of 10,000 mPa.s and 28 g of methyl vinyl raw rubber with a weight average molecular weight of 500,000 were mixed at room temperature and divided into two parts, 4.5 g of curing agent hydrogenated silicone oil was added to one part to obtain component A rubber, and 0.08 g of ethynyl cyclohexanol inhibitor and 1.5 g of platinum water catalyst were added to the other part to obtain component B rubber.

[0097] Comparative Example 4

[0098] This comparative example provides a heat-conductive absorbing gasket, and its preparation method is substantially the same as the preparation method in Example 1, except that: in step (2), the absorbing filler and the heat-conductive filler are not mixed and surface-modified.

[0099] Step (2) specifically includes: putting 750g of spherical alumina with a particle size of 120μm, 200g of spherical alumina with a particle size of 10μm, 55g of quasi-spherical alumina with a particle size of 0.6μm, 150g of spherical aluminum nitride powder with a particle size of 30μm and 500g of spherical carbonyl iron powder into a reactor, and stirring and mixing at 80°C for 1h.

[0100] Performance testing and results

[0101] The performance of the heat-conducting and wave-absorbing gaskets prepared in the examples and comparative examples was tested, and the specific testing method is as follows:

[0102] (1) Thermal conductivity: The thermal conductivity of the product is tested according to ASTM D 5470;

[0103] (2) Hardness: Test the hardness of the product according to ASTM D 2240;

[0104] (3) Reflection loss: According to the GJB2038A-2011 test standard, the reflection loss of the product is tested using the bow reflection method;

[0105] (4) Volatility rate: Place 10 g of sample in a glass dish and bake it on a baking table at 125°C for 24 h. Measure the weight difference before and after the product is tested and calculate the weight loss ratio as the volatility rate.

[0106] (5) Oil diffusion: Place a sample with a diameter of 30 mm on filter paper, cover it with filter paper, and place a 1 kg weight on the filter paper for compression. Place it in an oven at 125 °C for 72 h, and then take it out to measure the distance the product diffuses on the filter paper.

[0107] (6) Rebound rate: The compression amount of the heat-conducting and wave-absorbing gasket is controlled to 50%, and the pressure is released after a residence time of 30 minutes, and the rebound amount after 30 minutes is recorded.

[0108] The above performance test results are shown in Table 3.

[0109] Table 3 Performance test results of embodiments and comparative examples

[0110]

[0111] From the performance test results in Table 3, it can be seen that in Examples 1 to 7 of the present application, by using vinyl silicone oil and methyl vinyl rubber as the mixed resin matrix, and performing vacuum heating and stirring pretreatment, combined with mixed surface modification of the absorbing filler and the thermal conductive filler, the synergistic effect makes the prepared thermal conductive absorbing gasket have high thermal conductivity, good wave absorbing properties, low volatility, low oil diffusion and high elasticity. Among them, the thermal conductivity is not less than 5w / mk, the reflection loss at 25Ghz can be as low as -39dB / mm, the volatility is not higher than 0.04%, the oil diffusion is not higher than 1.0%, and the rebound rate is not lower than 85%.

[0112] By comparing the performance test results of Example 1 and Comparative Examples 1 to 4, it can be seen that in Comparative Example 1, no methyl vinyl rubber is added, no vacuum heating and stirring pretreatment is performed on the silicone resin, and no surface modification is performed on the thermal conductive filler and the wave absorbing filler. The thermal conductivity, wave absorption and resilience of the obtained thermal conductive wave absorbing gasket are significantly reduced, and the volatility and oil diffusion values ​​are significantly increased, which cannot meet the application requirements of electronic components, especially cannot be used in closed security or optical module components. In Comparative Example 2, no methyl vinyl rubber is added, the resilience of the product is significantly reduced, the volatility and oil diffusion are significantly increased, and the problem of poor contact caused by the long assembly compression time of conventional products cannot be solved, and the thermal conductivity and wave absorbing performance are also slightly reduced. In Comparative Example 3, no vacuum heating and stirring pretreatment is performed, resulting in a significant increase in volatility and oil diffusion. In Comparative Example 4, no surface modification is performed on the thermal conductive filler and the wave absorbing filler, resulting in a decrease in the compatibility of the powder filler with the resin, a decrease in the effective filling amount, resulting in a significant decrease in thermal conductivity and wave absorbing performance, and a significant increase in volatility and oil diffusion values.

[0113] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

Claims

1. A method for preparing a thermally conductive wave-absorbing gasket, characterized in that: The following steps are involved: Pretreatment of organic silicon resin: vinyl silicone oil and methyl vinyl rubber are heated and stirred in vacuum to obtain an organic silicon resin matrix; The organic silicon resin matrix is ​​divided into two parts, a curing agent is added to one part to obtain a component A rubber material, and an inhibitor and a catalyst are added to the other part to obtain a component B rubber material; Powder surface modification: Use silane coupling agent to coat and modify the thermal conductive filler and the wave absorbing filler to obtain a mixed modified filler; Forming of heat-conducting wave-absorbing gasket: The rubber material of component A, the rubber material of component B and the mixed modified filler are mixed, pressed into shape, and heated and cured to obtain the heat-conducting wave-absorbing gasket.

2. The preparation method according to claim 1, characterized in that: The weight average molecular weight of the methyl vinyl raw rubber is 500,000 to 700,000.

3. The preparation method according to claim 1, characterized in that: The vacuum heating stirring and mixing conditions in the silicone resin pretreatment step include: continuous stirring at 80-150° C. for 1-2 hours.

4. The preparation method according to claim 1, characterized in that: The powder surface modification treatment step comprises: The wave absorbing filler and the thermal conductive filler with different particle sizes are stirred and mixed to obtain a mixed filler; Mixing and diluting the silane coupling agent with ethanol to obtain a modified solution; Under heating and stirring conditions, spraying the modified solution onto the surface of the mixed filler to obtain the mixed modified filler; Optionally, the heating and stirring is carried out at a temperature of 80 to 100° C. and for a time of 0.5 to 1 h.

5. The preparation method according to claim 1, characterized in that: The thermally conductive filler comprises at least one of aluminum oxide, aluminum nitride or diamond, and the particle size of the thermally conductive filler is 0.1 to 120 μm; The wave absorbing filler comprises at least one of carbonyl iron powder, sendust powder, tin oxide and tin pyrophosphate powder; The silane coupling agent is a vinyl modified silane coupling agent.

6. The preparation method according to any one of claims 1 to 5, characterized in that: Based on the total weight of the thermally conductive wave-absorbing gasket, the weight percentages of the components in the silicone resin pretreatment step are respectively: 55-105 parts of vinyl silicone oil of different viscosities, 20-30 parts of methyl vinyl rubber, 3-8 parts of curing agent, 0.05-0.2 parts of inhibitor, 1-3 parts of catalyst; Optionally, the vinyl silicone oil includes 15 to 35 parts of vinyl silicone oil with a viscosity of 100 to 200 mPa.s, 15 to 35 parts of vinyl silicone oil with a viscosity of 400 to 600 mPa.s, and 15 to 25 parts of vinyl silicone oil with a viscosity of 8000 to 10000 mPa.s.

7. The preparation method according to any one of claims 1 to 5, characterized in that: Based on the total weight of the thermally conductive and absorbing gasket, the weight portions of the components in the powder surface modification treatment step are: 1000-1500 parts of thermally conductive fillers of different particle sizes, and 400-600 parts of absorbing fillers; Optionally, the thermally conductive filler includes 700-900 parts of spherical alumina with a particle size of 90-120 μm, 50-200 parts of spherical alumina with a particle size of 10-20 μm, 50-90 parts of quasi-spherical alumina with a particle size of 0.5-2 μm, and 100-230 parts of spherical aluminum nitride with a particle size of 30-50 μm.

8. The preparation method according to claim 1, characterized in that: In the step of forming the thermally conductive and absorbing gasket, the mixing method includes: Mixing part of the mixed modified filler with the rubber material of component A to obtain a mixed rubber material of component A; Mixing another portion of the mixed modified filler with the component B rubber material to obtain a component B mixed rubber material; The mixed rubber material of component A and the mixed rubber material of component B are mixed, and the mixture is continuously stirred and mixed under vacuum at a temperature below 30° C. for 30 to 180 minutes.

9. A heat-conducting and wave-absorbing gasket, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the heat-conducting and wave-absorbing gasket according to claim 9 in electronic components.

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