Shielding silica gel and preparation method and application thereof

Abstract

The application relates to the technical field of shielding silica gel processing, in particular to a shielding silica gel and a preparation method and application thereof, which are prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber, 10-20 parts of a plasticizer, 8-12 parts of fumed white carbon black, 2-4 parts of hydroxyl silicone oil, 120-200 parts of graphite, 20-30 parts of a modified dispersant, 5-10 parts of carbon nanotubes, 5-10 parts of carbon black, 0.2-0.5 parts of a vulcanizing agent, and 0-4 parts of a silane coupling agent; the plasticizer is composed of dodecamethylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil; the modified dispersant is composed of polyoxyethylene hydrogenated castor oil, a diphenylsilanediol alcohol solution and hexamethylcyclotrisilazane; by adopting the above formula, the shielding silica gel still has low compression permanent deformation and high resilience under an ultrahigh filling amount, the shielding and conductive performances of the shielding silica gel are greatly improved, and the problems of limited shielding effect, increased compression permanent deformation and reduced resilience of the existing shielding silica gel are solved.

Description

Technical Field

[0001] This application relates to the field of shielding silicone processing technology, and more specifically, to a shielding silicone, its preparation method, and its application. Background Technology

[0002] As electronic devices evolve towards higher frequencies and higher speeds, the operating frequencies of processors, memory chips, and high-speed signal lines in high-performance computing devices such as servers and mainframe computers are constantly increasing, leading to increasingly prominent electromagnetic interference problems. Shielding silicone is a silicone rubber material reinforced with conductive fillers, capable of achieving efficient electromagnetic shielding and environmental sealing. Carbon nanotubes, as a one-dimensional nanomaterial, possess extremely high aspect ratios, excellent conductivity, and good mechanical strength. Conductive silicone prepared by filling a silicone matrix with carbon nanotubes as conductive fillers can form an effective conductive network at relatively low filler amounts, achieving highly efficient electromagnetic shielding, particularly in the field of high-frequency electromagnetic shielding. However, carbon nanotubes are expensive, and the strong van der Waals forces between them make them prone to entanglement and aggregation, making uniform dispersion in the silicone matrix difficult. Therefore, the addition amount is generally limited to no more than 5% of the silicone; otherwise, the compression set and resilience of the finished silicone product will decrease significantly, failing to meet the requirements for long-term elasticity retention. Adding no more than 5% results in the conductivity and shielding effectiveness of the silicone product approaching saturation, making it impossible to achieve performance breakthroughs by further increasing the amount.

[0003] To further improve the conductivity and shielding performance of shielding silicone, conductive fillers such as conductive metals and graphite are often added in combination. However, this still sacrifices the elastic recovery performance of the silicone matrix, resulting in increased compression set and reduced resilience, which cannot meet the stringent requirements for long-term elasticity maintenance in products such as server seals and heat sinks. Summary of the Invention

[0004] To address the limitations of existing shielding silicone in terms of shielding effectiveness, increased compression set, and reduced resilience, this application provides a shielding silicone, its preparation method, and its applications.

[0005] Firstly, this application provides a shielding silicone material, employing the following technical solution: A shielding silicone is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber 10-20 parts plasticizer 8-12 parts of fumed silica 2-4 parts of hydroxy silicone oil 120-200 parts of graphite 20-30 parts of modified dispersant 5-10 parts of carbon nanotubes 5-10 parts carbon black 0.2-0.5 parts of vulcanizing agent 0-4 parts of silane coupling agent; The plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil; The modified dispersant is composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution and hexamethylcyclotrisilazane.

[0006] By adopting the above technical solution, the conductivity and shielding performance of the shielding silicone are significantly improved, while maintaining excellent elastic recovery performance.

[0007] This application introduces a large amount of graphite in combination with carbon nanotubes and carbon black, enabling the shielding silicone to form a conductive network. Graphite forms the basic conductive pathway, carbon nanotubes provide the highly efficient conductive network required for high-frequency shielding, and carbon black fills the microscopic gaps to optimize conductive continuity. The combined use of these three elements significantly improves the overall conductivity and electromagnetic shielding effect of the shielding silicone, especially in high-frequency electromagnetic environments. However, due to the addition of a large amount of graphite, it tends to clump together, making it difficult to ensure that the graphite is fully and evenly distributed in the silicone matrix. Furthermore, a high proportion of graphite can make the compound excessively viscous, hindering processing. This application effectively solves the dispersion problem and processing obstacles of highly filled graphite by using a dispersant composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution, and hexamethylcyclotrisilazane. This ensures that the compound maintains good flowability and roll wrapping properties during mixing, guaranteeing uniform dispersion of graphite in the silicone matrix. Among them, the polyoxyethylene hydrogenated castor oil provides lubrication and prevents graphite agglomeration; the silanol groups in the diphenylsilanediol solution form hydrogen bonds with the oxygen-containing functional groups on the graphite surface, improving the interfacial compatibility between graphite and silicone rubber, reducing interfacial tension, and enabling graphite to be uniformly dispersed in the rubber compound; hexamethylcyclotrisilazane forms an organosilicon modified layer on the graphite surface through the chemical reactivity of silicon-nitrogen bonds, further enhancing the bonding force between the filler and the matrix.

[0008] Graphite is a rigid material, and its addition in large quantities can severely disrupt the flexible cross-linked elastic network of silicone rubber, leading to reduced elasticity and increased compression set of the silicone. This application addresses these issues by using a composite plasticizing system composed of dodecylcyclohexasiloxane, epoxy silicone oil, and alkoxy silicone oil. Dodecylcyclohexasiloxane, as a low-viscosity silicone oil, can intercalate between silicone rubber molecular chains, increasing their slippage and keeping the silicone flexible. Epoxy silicone oil reacts with graphite, carbon nanotubes, carbon black surfaces, and silicone rubber molecules through its epoxy groups, forming a flexible interface layer that enhances the bond between the filler and the matrix while providing buffer space for molecular chain movement. Alkoxy silicone oil participates in the vulcanization reaction, optimizing the cross-linked network structure. This composite plasticizing system, in combination with modified dispersants, solves the problem of rigid fillers directly damaging the elastic network of silicone rubber. This allows the material to maintain good softness and elastic recovery ability even under high filler conditions, with low compression set and high elasticity retention after long-term use, meeting the stringent requirements for long-term elasticity retention in products such as server seals and heat sinks.

[0009] Preferably, the weight ratio of the polyoxyethylene hydrogenated castor oil, the diphenylsilanediol solution, and the hexamethylcyclotrisilazane is (3-4):(8-10):1.

[0010] By adopting the above technical solution and optimizing the dispersant ratio, the lubricating effect of polyoxyethylene hydrogenated castor oil and the improved interfacial compatibility of diphenylsilanediol solution are balanced. This effectively prevents graphite agglomeration and reduces interfacial tension by forming stable hydrogen bonds between the silanol groups and oxygen-containing functional groups on the graphite surface. Simultaneously, the content of hexamethylcyclotrisilazane is relatively moderate, ensuring the formation of a sufficient organosilicon modified layer on the graphite surface to enhance the bonding force between the filler and the matrix, while avoiding cross-linking interference that may result from excessive silazane. This modified ratio better solves the dispersion problem and processing obstacles of highly filled graphite, maintaining good fluidity of the compound during mixing, ensuring uniform dispersion of graphite in the silicone matrix, and maintaining the integrity of the graphite conductive network. This ensures that the shielding silicone has excellent conductivity and electromagnetic shielding effects.

[0011] Preferably, the weight ratio of the dodecylcyclohexasiloxane, the epoxy silicone oil, and the alkoxy silicone oil is (1-2):9:(3-5).

[0012] Preferably, the alkoxy silicone oil is a low molecular weight alkoxy silicone oil with a molecular weight of 5000-10000.

[0013] By adopting the above technical solution and optimizing the plasticizer dosage ratio, epoxy silicone oil, as the main component, allows its epoxy groups to fully react with graphite, carbon nanotubes, carbon black surfaces, and silicone rubber molecules, forming a uniform and continuous flexible interface layer that effectively buffers the direct damage to the elastic network caused by rigid fillers. The relatively low content of dodecylcyclohexasiloxane, as a low-viscosity silicone oil, is appropriately inserted between the silicone rubber molecular chains, maintaining the molecular chain slippage ability while avoiding the strength reduction that may result from excessive low-molecular-weight silicone oil. The moderate content of alkoxy silicone oil allows it to fully participate in the vulcanization reaction and optimize the cross-linking network structure without causing abnormal cross-linking density or changes in vulcanization characteristics due to excessive alkoxy groups. Simultaneously, the molecular weight of alkoxy silicone oil (5000-10000) is moderate, allowing it to smoothly integrate into the rubber molecular chains and play its role without easily volatilizing or migrating due to its low molecular weight. This formulation ensures optimal synergy between the composite plasticizer and the modified dispersant. While addressing the issues of increased compression set and reduced resilience caused by high graphite filler, it also ensures that the shielding silicone maintains excellent softness, elastic recovery, and elasticity retention even under high filler conditions, meeting the stringent requirements for long-term elasticity retention in products such as server seals and heat sinks.

[0014] Preferably, the graphite is pretreated by the following method: By weight, 100 parts of graphite and 200-300 parts of hydroxide solution are ball-milled, filtered, rinsed, and dried. Then, 8-15 parts of graphite and long-chain alkyl POSS are stirred at 50-60°C to obtain pretreated graphite.

[0015] By employing the above technical solution, graphite is more uniformly dispersed in silicone rubber, resulting in smoother processing. First, graphite is ball-milled with an alkaline solution to clean the surface and introduce oxygen-containing functional groups to increase activity. Then, it reacts with long-chain alkyl POSS. The long-chain alkyl POSS forms chemical bonds with the graphite surface through its siloxane backbone, enhancing the interfacial compatibility between graphite and the silicone rubber matrix and effectively preventing graphite particle agglomeration. This pretreatment process, combined with the modified dispersant system, further improves the uniformity of graphite dispersion in the silicone rubber matrix. Simultaneously, it improves the interfacial bonding strength between the filler and the matrix. While maintaining high conductivity and electromagnetic shielding effectiveness, it effectively mitigates the damage to the elastic network of silicone rubber caused by highly filled graphite, optimizing the processing flowability, mechanical properties, and elastic recovery ability of the shielding silicone rubber.

[0016] Preferably, the long-chain alkyl POSS is epoxy-POSS or mercapto-POSS.

[0017] Preferably, the mercapto-POSS is mainly soluble in acetone solution, forming a solution state.

[0018] By employing the above technical solution, epoxy-POSS or mercapto-POSS, as a graphite pretreatment agent, can form a stronger chemical bond with the graphite surface. The epoxy or mercapto groups can react with the active groups on the graphite surface after alkaline treatment, causing POSS to adhere firmly to the graphite surface and preventing it from easily detaching. This strong bonding force improves the compatibility of graphite with the silicone matrix, resulting in more uniform dispersion and reducing the likelihood of re-aggregation. Simultaneously, the epoxy groups can further react with silicone molecules, while the mercapto groups can participate in the vulcanization process, making the bond between graphite and rubber even tighter. The resulting shielding silicone exhibits stable conductivity, is soft and elastic, and maintains good resilience even after long-term use, meeting the requirements for seals and heat dissipation pads.

[0019] Preferably, the carbon nanotubes have a length of 10-30 mm and an outer diameter of 10-20 nm, the graphite has an average particle size of 30-50 mm, and the carbon black has an average particle size of 0.03-0.05 mm.

[0020] By adopting the above technical solution, a reasonable combination of the three conductive fillers in terms of size was achieved. Longer carbon nanotubes can overlap within the silica gel to form a highly efficient conductive network, suitable for high-frequency electromagnetic shielding; medium-sized graphite serves as the main filler, providing a basic conductive path and reducing costs; ultrafine carbon black fills the tiny gaps between the graphite and carbon nanotubes, repairing breaks in the conductive network. The synergy of these three fillers of different sizes makes the conductive path more continuous and complete, significantly improving the conductivity and electromagnetic shielding effect of the shielding silica gel.

[0021] Preferably, the methyl vinyl silicone rubber has a relative molecular weight of 600,000-700,000 and a vinyl content of 0.17-0.27%.

[0022] By adopting the above technical solutions and optimizing the parameters of methyl vinyl silicone rubber, the rubber compound is guaranteed to have sufficient strength and elasticity, while avoiding excessive viscosity and difficulty in mixing and processing due to excessively high molecular weight. At the same time, the appropriate vinyl content ensures a moderate vulcanization reaction rate and reasonable crosslinking density, which can form a stable elastic network without affecting the operation time and the elastic properties of the final product due to excessively fast or dense crosslinking.

[0023] Preferably, the hydroxyl silicone oil has a number-average molecular weight of 800-3000 and a hydroxyl content of 3-12%. By adopting the above technical solution and optimizing the parameters of hydroxyl silicone oil, it can fully wet the surface of fillers such as graphite and carbon nanotubes, without easily volatilizing and migrating due to excessively low molecular weight or increasing the viscosity of the rubber compound due to excessively high molecular weight. The appropriate hydroxyl content enables it to form appropriate interactions with the active groups on the surface of the filler and the silicone rubber molecules, helping the filler to be evenly dispersed during the mixing process and preventing agglomeration. At the same time, it can also work with silane coupling agents to enhance the bonding force between the filler and the silicone matrix.

[0024] Secondly, this application provides a method for preparing shielding silicone, which adopts the following technical solution: A method for preparing a shielding silicone material includes the following preparation steps: S1. First, thoroughly stir the carbon nanotubes and silane coupling agent, then add graphite, carbon black and dispersant and stir thoroughly to obtain a mixed solid; S2. Methyl vinyl silicone rubber, fumed silica, hydroxyl silicone oil, plasticizer and mixed solids are mixed and then a vulcanizing agent is added and mixed and vulcanized to obtain shielding silicone.

[0025] Preferably, the mixing temperature is 70-80℃, and the vulcanization process is as follows: the first vulcanization is carried out at a temperature of 165-175℃, a pressure of 10-15MPa, and a time of 5-10min, and then the second vulcanization is carried out at a temperature of 180-200℃ and a time of 2-4h.

[0026] By adopting the above technical solution, the first step involves thoroughly stirring carbon nanotubes and a silane coupling agent to pre-coat the surface of the carbon nanotubes, improving their dispersibility. Then, graphite, carbon black, and a dispersant are added and stirred together to ensure the three conductive fillers are pre-mixed evenly in a solid state, forming a preliminary conductive filler assembly. The second step involves mixing this solid mixture with silicone rubber, fumed silica, hydroxyl silicone oil, and a plasticizer to uniformly integrate the pre-dispersed conductive filler into the silicone matrix. Finally, a vulcanizing agent is added to complete the cross-linking reaction. This step-by-step feeding method avoids the problem of agglomeration when carbon nanotubes and graphite are directly added to the rubber compound, ensuring a uniform formation of the conductive network in the silicone. The resulting shielding silicone exhibits stable conductivity, good electromagnetic shielding effect, smooth processing, and a soft, elastic finished product with minimal deformation after long-term use.

[0027] Thirdly, this application provides an application of shielding silicone, employing the following technical solution: An application of shielding silicone, the shielding silicone being used for shielding silicone pads, the shielding silicone pads comprising a release layer, an adhesive layer, and a shielding silicone layer.

[0028] By adopting the above technical solution, the shielding silicone pad retains the material's good conductive network, soft elasticity, and long-term rebound characteristics, while also possessing the easy installation and replacement features required for practical applications. It is particularly suitable for applications such as servers and communication equipment that have strict requirements for electromagnetic shielding and heat dissipation sealing, and can stably perform the dual functions of shielding and sealing for a long time.

[0029] In summary, this application has the following beneficial effects: This application's shielding silicone utilizes a conductive network constructed with a large amount of graphite, carbon nanotubes, and carbon black to enhance conductivity and electromagnetic shielding performance, exhibiting particularly excellent performance in high-frequency environments. A modified dispersant composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution, and hexamethylcyclotrisilazane is employed to solve the dispersion challenges and processing obstacles of highly filled graphite, ensuring uniform graphite dispersion. Simultaneously, a composite plasticizing system composed of dodecylcyclohexasiloxane, epoxy silicone oil, and alkoxy silicone oil effectively mitigates the damage to the elastic network caused by rigid fillers, enabling the material to maintain good elastic recovery and low compression set even at high filler levels, meeting the stringent requirements for long-term elasticity retention in products such as server seals and heat sinks. Detailed Implementation Example

[0030] The polyoxyethylene hydrogenated castor oil is BASF's Kolliphor® RH 40.

[0031] The diphenylsilanediol solution is obtained by dissolving diphenylsilanediol in anhydrous ethanol, with a concentration of 10%.

[0032] The epoxy silicone oil is γ-glycidyl etheroxypropyltrimethoxy silicone oil with a molecular weight of 2000. Alkoxy silicone oil is methyltriethoxy silicone oil with a molecular weight of 5000.

[0033] Example 1 A shielding silicone is prepared by the following method: S1. First, stir 5g of carbon nanotubes and 0g of silane coupling agent thoroughly, then add 120g of graphite, 5g of carbon black and 20g of dispersant and stir thoroughly to obtain a mixed solid. The carbon nanotubes are 10 mm long and 10 nm in outer diameter, the graphite has an average particle size of 30 mm, and the carbon black has an average particle size of 0.03 mm. The modified dispersant is composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution, and hexamethylcyclotrisilazane in a weight ratio of 3:8:1. S2. Mix 100g of methyl vinyl silicone rubber, 8g of fumed silica, 2g of hydroxyl silicone oil, 10g of plasticizer and mixed solids until all raw materials are fully mixed and uniform. Then add 0.2g of vulcanizing agent and mix and vulcanize to obtain shielding silicone. The relative molecular weight of methyl vinyl silicone rubber is 600,000, and the vinyl content is 0.17%. The number average molecular weight of the hydroxyl silicone oil is 800, and the hydroxyl content is 3%. The plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil in a weight ratio of 1:9:3; The mixing temperature is 70℃, and the vulcanization process is as follows: First vulcanization is carried out at a temperature of 165℃, a pressure of 10MPa, and a time of 5min. Then, a second vulcanization is carried out at a temperature of 180℃ and a time of 2h.

[0034] The difference between Examples 2-3 and Example 1 lies in the types, amounts, and parameters of raw materials used to prepare the shielding silicone. Specific differences are shown in Table 1. Table 1. Types, dosages, and parameters of raw materials used in the preparation of shielding silicone.

[0035] Example 4

[0036] A shielding silicone, the difference between this embodiment and Embodiment 1 is that the dispersant is composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution and hexamethylcyclotrisilazane in a weight ratio of 3:3:1.

[0037] Example 5 A shielding silicone, the difference between this embodiment and Embodiment 1 is that the dispersant is composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution and hexamethylcyclotrisilazane in a weight ratio of 3:8:5.

[0038] Example 6 A type of shielding silicone, the difference between this embodiment and Embodiment 1 is that the graphite is pretreated using the following method. 120g of graphite and 240g of hydroxide solution (mass fraction of 5%) were ball-milled, filtered, rinsed, and dried. Then, graphite was mixed with 9.6g of long-chain alkyl POSS (epoxy-POSS) at 50°C and stirred for 2h to obtain pretreated graphite.

[0039] The epoxy-POSS was purchased from Xi'an Qiyue Biotechnology Co., Ltd., and is an octaglycidyl cage-type polysilsesquioxane.

[0040] Example 7 A type of shielding silicone, the difference between this embodiment and Embodiment 1 is that the graphite is pretreated using the following method. 120g of graphite and 360g of hydroxide solution were ball-milled, filtered, rinsed, and dried. Then, 18g of long-chain alkyl POSS (mercapto-POSS) was added to the graphite and stirred at 60°C for 3 hours to obtain pretreated graphite.

[0041] The mercapto-POSS was purchased from Xi'an Qiyue Biotechnology Co., Ltd., and is designated as POSS-SH.

[0042] Example 8 A shielding silicone, the difference between this embodiment and Embodiment 1 is that the plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil in a weight ratio of 1:1:3.

[0043] Example 9 A shielding silicone, the difference between this embodiment and Embodiment 1 is that the plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil in a weight ratio of 5:9:3.

[0044] Example 10 A shielding silicone, the difference between this embodiment and Embodiment 1 is that the plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil in a weight ratio of 1:9:1.

[0045] Comparative Example Comparative Example 1 A type of shielding silicone, the difference between this comparative example and Example 1 is that the amount of graphite is 50g and the amount of carbon black is 75g.

[0046] Comparative Example 2 A shielding silicone, the difference between this comparative example and Example 1 is that the modified dispersant is replaced with a modified borate ester, FS-79A.

[0047] Comparative Example 3 A shielding silicone, the difference between this comparative example and Example 1 is that the modified dispersant is composed of polyoxyethylene hydrogenated castor oil and hexamethylcyclotrisilazane in a weight ratio of 3:1.

[0048] Comparative Example 3 A shielding silicone, the difference between this comparative example and Example 1 is that the modified dispersant is composed of polyoxyethylene hydrogenated castor oil, zinc stearate and hexamethylcyclotrisilazane in a weight ratio of 3:8:1.

[0049] Comparative Example 4 A shielding silicone, the difference between this comparative example and Example 1 is that the modified dispersant is composed of diphenylsilanediol solution and hexamethylcyclotrisilazane in a weight ratio of 8:1.

[0050] Comparative Example 5 A shielding silicone, the difference between this comparative example and Example 1 is that the modified dispersant is composed of zinc stearate, diphenylsilanediol solution and hexamethylcyclotrisilazane in a weight ratio of 3:8:1.

[0051] Comparative Example 6 A type of shielding silicone, the difference between this comparative example and Example 1 is that the plasticizer is composed of dodecylcyclohexasiloxane and alkoxy silicone oil in a weight ratio of 1:3.

[0052] Comparative Example 7 A type of shielding silicone, the difference between this comparative example and Example 1 is that the plasticizer is composed of dodecylcyclohexasiloxane and epoxy silicone oil in a weight ratio of 1:9.

[0053] Comparative Example 8 A type of shielding silicone, the difference between this comparative example and Example 1 is that the plasticizer is composed of dioctyl phthalate, epoxy silicone oil and alkoxy silicone oil in a weight ratio of 1:9:3.

[0054] Comparative Example 9 A type of shielding silicone, the difference between this comparative example and Example 1 is that the plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and caprylic / capric glyceride in a weight ratio of 1:9:3.

[0056] Detection methods / test methods Tensile strength and elongation at break: tested according to ASTM D412; Compression set at room temperature: Tested according to GB / T 7759.1-2015 standard; Shielding performance test: The test was conducted in accordance with the ASTM D4935 standard; Surface resistivity: Surface resistivity was tested according to GB / T 40719-2021. Experimental data are shown in Table 2. Table 2 Experimental data of Examples 1-10 and Comparative Examples 1-9

[0057] The experimental data above show that the formulation in this application improves the shielding and conductivity of the shielding silicone by increasing the amount of graphite, while maintaining good elastic recovery and low compression set even with high filling.

[0058] Compared with Example 1, Comparative Example 1 has good mechanical properties and resilience, but its shielding performance and conductivity are greatly reduced, which does not meet product requirements. In Comparative Examples 2-5, the use of other dispersants and the substitution or reduction of the amount of a certain component in the dispersant resulted in the mechanical properties, resilience, shielding effect, and conductivity of the shielding silicone being inferior to those of Example 1. This indicates that the modified dispersant system composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution, and hexamethylcyclotrisilazane has a positive effect on solving the problem of difficult dispersion of highly filled graphite, and can improve the mechanical properties, resilience, shielding effect, and conductivity of the shielding silicone. In Comparative Examples 6-9, replacing or reducing the amount of a certain component in the plasticizer resulted in the mechanical properties, resilience, shielding effect, and conductivity of the shielding silicone being inferior to those of Example 1. This demonstrates that the composite plasticizing system of dodecylcyclohexasiloxane, epoxy silicone oil, and alkoxy silicone oil can improve the mechanical properties, resilience, shielding effect, and conductivity of the shielding silicone.

[0059] Compared with Example 1, the mechanical properties, resilience, shielding effect and conductivity of Examples 4-5 all decreased, indicating that optimizing the amount of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution and hexamethylcyclotrisilazane is beneficial to ensure uniform dispersion of highly filled graphite, complete and continuous conductive network and excellent elastic recovery performance.

[0060] Compared with Example 1, the mechanical properties, resilience, shielding effect, and conductivity of Examples 6-7 are all improved, indicating that the pretreatment of graphite by the method of this application is beneficial to the uniform dispersion of graphite, thereby improving the mechanical properties, resilience, shielding effect, and conductivity of the shielding silicone.

[0061] Compared with Example 1, the mechanical properties, resilience, shielding effect, and conductivity of Examples 8-9 all decreased, indicating that optimizing the amount of dodecylcyclohexasiloxane, epoxy silicone oil, and alkoxy silicone oil is beneficial to improving the mechanical properties, resilience, shielding effect, and conductivity of highly filled graphite shielding silicone.

[0062] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of shielding silicone, characterized in that, It is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber 10-20 parts plasticizer 8-12 parts of fumed silica 2-4 parts of hydroxy silicone oil 120-200 parts of graphite 20-30 parts of modified dispersant 5-10 parts of carbon nanotubes 5-10 parts carbon black 0.2-0.5 parts of vulcanizing agent 0-4 parts of silane coupling agent; The plasticizer is composed of dodecylcyclohexasiloxane, epoxy silicone oil and alkoxy silicone oil; The modified dispersant is composed of polyoxyethylene hydrogenated castor oil, diphenylsilanediol solution and hexamethylcyclotrisilazane.

2. The shielding silicone according to claim 1, characterized in that: The polyoxyethylene hydrogenated castor oil, the diphenylsilanediol solution, and the hexamethylcyclotrisilazane are composed in a weight ratio of (3-4):(8-10):

1.

3. The shielding silicone according to claim 1, characterized in that: The weight ratio of the dodecylcyclohexasiloxane, the epoxy silicone oil, and the alkoxy silicone oil is (1-2):9:(3-5).

4. The shielding silicone according to claim 3, characterized in that, The graphite is pretreated using the following method. By weight, 100 parts of graphite and 200-300 parts of hydroxide solution are ball-milled, filtered, rinsed, and dried. Then, 8-15 parts of graphite and long-chain alkyl POSS are stirred at 50-60°C to obtain pretreated graphite.

5. The shielding silicone according to claim 1, characterized in that: The long-chain alkyl POSS is an epoxy-POSS or a mercapto-POSS.

6. The shielding silicone according to claim 1, characterized in that: The carbon nanotubes have a length of 10-30 mm and an outer diameter of 10-20 nm, the graphite has an average particle size of 30-50 mm, and the carbon black has an average particle size of 0.03-0.05 mm.

7. The shielding silicone according to claim 1, characterized in that: The methyl vinyl silicone rubber has a relative molecular weight of 600,000-700,000 and a vinyl content of 0.17-0.27%.

8. The shielding silicone according to claim 1, characterized in that: The hydroxyl silicone oil has a number average molecular weight of 800-3000 and a hydroxyl content of 3-12%.

9. A method for preparing the shielding silicone as described in any one of claims 1-8, characterized in that, The preparation steps include the following: S1. First, thoroughly stir the carbon nanotubes and silane coupling agent, then add graphite, carbon black and dispersant and stir thoroughly to obtain a mixed solid; S2. Methyl vinyl silicone rubber, fumed silica, hydroxyl silicone oil, plasticizer and mixed solids are mixed and then a vulcanizing agent is added and mixed and vulcanized to obtain shielding silicone.

10. An application of the shielding silicone as described in claims 1-8 or the shielding silicone prepared in claim 9, characterized in that: The shielding silicone is used for shielding silicone pads, which include a release layer, an adhesive layer, and a shielding silicone layer.

Images