Rebounding heat-conducting silica gel gasket and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting silica gel gaskets, and particularly relates to a rebounding heat-conducting silica gel gasket and a preparation method thereof.The rebounding heat-conducting silica gel gasket is prepared from, by weight, 100 parts of vinyl silicone oil; 600 to 1000 parts of a treated heat-conducting filler with a large particle size; 100 to 300 parts of small particle size spherical alumina; 10 to 30 parts of graphene slurry; 5-10 parts of hydrogen-containing silicone oil; and 0.2 to 0.5 part of a catalyst. A high-efficiency heat-conducting network is constructed through graphene, and a combination of a mixture of large-particle-size spherical aluminum nitride and spherical aluminum oxide and small-particle-size spherical aluminum oxide is combined; meanwhile, the gasket is endowed with excellent resilience through a chelating dispersant enhanced cross-linked network, surface elastic coating treatment of the large-particle-size heat-conducting filler and a synergistic effect of graphene, and excellent balance of high heat conductivity and high resilience is realized.

Description

Technical Field

[0001] This invention relates to a resilient thermally conductive silicone pad and its preparation method, belonging to the technical field of thermally conductive silicone pads. Background Technology

[0002] With the rapid development of electronic technology, the integration and power of electronic devices are constantly increasing, and the heat density of electronic components is increasing dramatically, posing a severe challenge to their heat dissipation management. Thermally conductive silicone pads, as an important thermal interface material (TIM), are widely used to fill the assembly gaps between heat-generating components (such as CPUs and GPUs) and heat sinks (such as heat sinks and cold plates) due to their good thermal conductivity and insulation properties, in order to eliminate air, reduce contact thermal resistance, and improve heat dissipation efficiency.

[0003] However, in practical applications, especially under complex conditions such as automotive electronics and mobile devices, the gaps at the heat dissipation interface may dynamically change due to vibration, thermal expansion and contraction, or structural deformation (fluctuations can reach 30%). Furthermore, the assembly positions are diverse, and there are even requirements for vertical assembly. This places higher demands on the overall performance of thermally conductive silicone gaskets. Traditional thermally conductive gaskets, in pursuit of high thermal conductivity (e.g., reaching 10 W / m·K), are typically filled with a large amount of thermally conductive filler, resulting in a relatively reduced polymer matrix content. This leads to high gasket hardness and poor resilience (typically a high compression set and a rebound rate of less than 10%). When the assembly gap increases, these highly filled gaskets cannot rebound in time to maintain a tight fit, easily creating gaps or localized detachment at the interface, causing a sharp increase in thermal resistance and even heat dissipation failure. In addition, gaskets with poor resilience are prone to creep or displacement under long-term stress, further affecting the reliability of heat dissipation.

[0004] Therefore, developing a thermal pad that combines high thermal conductivity and high resilience, can dynamically adapt to changes in the gaps of the heat dissipation interface, and has good interface adhesion has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing high thermal conductivity silicone pads, such as poor resilience and inability to adapt to dynamic gap changes, and to provide a thermally conductive silicone pad with both high thermal conductivity and high compression resilience, as well as its preparation method.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a resilient thermally conductive silicone pad, comprising, by weight, the following raw materials: 100 parts vinyl silicone oil; 600-1000 parts of treated large-particle-size thermally conductive filler; 100-300 parts of small-particle-size spherical alumina; 10-30 parts of graphene slurry; 5-10 parts of hydrogen-containing silicone oil; Catalyst 0.2 to 0.5 parts.

[0007] Furthermore, the preparation of the treated large-particle-size thermally conductive filler includes: thoroughly mixing large-particle-size thermally conductive particles with a surface treatment agent, then adding thermally conductive gel, reacting at 80-100°C for 15-30 minutes, and obtaining the treated large-particle-size thermally conductive filler after cooling.

[0008] Furthermore, the large-diameter thermally conductive particles are a mixture of spherical aluminum nitride and spherical aluminum oxide with an average particle size of 100-150 μm in a 1:1 mass ratio; the surface treatment agent is a long-chain alkyl silane, preferably CX-5569 from Guangzhou Chenxi; and the thermally conductive gel is a high-resilience silicone resin gel, preferably CX-3936 from Guangzhou Chenxi.

[0009] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: By composing large-particle thermally conductive particles with spherical aluminum nitride and spherical alumina of an average particle size of 100-150 μm in a 1:1 mass ratio, the excellent thermal conductivity of both (aluminum nitride has high thermal conductivity and good insulation, while alumina has relatively low cost and good stability) is utilized to form a synergistic effect, providing a macroscopically efficient thermal conduction pathway for the gasket; using long-chain alkylsilanes as surface treatment agents, their molecular chains can effectively improve the interfacial compatibility between the large-particle thermally conductive particles and the organosilicon matrix, reducing interfacial thermal resistance. At the same time, the long-chain structure can impart a certain degree of lubrication between the particles, which is beneficial to the dispersion of the thermally conductive filler in the matrix; and the introduction of high-resilience silicone resin gel with large-particle thermally conductive particles at 80-100 μm... Reaction at 0℃ for 15–30 minutes allows the high resilience of the silicone resin gel to partially "graft" onto the surface of rigid, large-diameter thermally conductive particles. When the gasket is subjected to compressive force, the gel layer can deform and absorb energy, driving the particles to reset after unloading, thereby enhancing the overall resilience potential of the gasket. On the other hand, the reaction process further strengthens the bonding of the surface treatment agent to the particle surface and may form flexible connection points between particles, avoiding stress concentration and increased brittleness caused by direct contact of rigid particles in traditional high-filling systems. This allows the large-diameter thermally conductive filler to maintain a good bonding state and deformation capacity with the matrix even at high filling amounts (600–1000 parts), laying a key foundation for achieving both high thermal conductivity and good resilience.

[0010] Furthermore, the graphene slurry is prepared from the following raw materials in parts by weight: 5-15 parts dimethyl silicone oil, 30-50 parts single-crystal alumina, 1-3 parts silane coupling agent, 1-5 parts graphene, and 0.1-1 parts chelating dispersant.

[0011] Furthermore, the dimethyl silicone oil has a viscosity of 50–100 mPa·s; the single-crystal alumina has an average particle size of 15–25 μm; and the graphene is a multilayer graphene powder with ≤10 layers, a sheet diameter ≤10 μm, and a specific surface area of ​​180–280 m². 2 / g, wherein the chelating dispersant is a compound having a telechelic structure.

[0012] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: Using dimethyl silicone oil with a viscosity of 50–100 mPa·s as the dispersion medium for the graphene slurry, dimethyl silicone oil in this viscosity range possesses both good fluidity and dispersion stability. This provides a uniform bearing environment for subsequently added solid particles and avoids difficulties in mixing due to excessively high viscosity or ineffective particle encapsulation due to excessively low viscosity. Using single-crystal alumina with an average particle size of 15–25 μm, its single-crystal structure exhibits higher crystal integrity and thermal conductivity. Furthermore, this particle size falls between that of large-diameter thermally conductive particles (100–150 μm) and small-diameter spherical alumina (0.5–5 μm). Between μm, it can precisely fill the gaps between large-diameter particles, forming a tight gradient stacking structure with thermally conductive fillers of different sizes, further optimizing the continuity of the thermally conductive network; using multilayer graphene powder, its layered structure can construct two-dimensional thermally conductive pathways in the slurry, intertwining with the three-dimensional thermally conductive network of spherical particles, significantly improving thermal conductivity; adding a chelating dispersant with a telechelic structure, which, while dispersing graphene and fillers, can also act as an additional crosslinking point to chemically bond to the three-dimensional network of silicone rubber, thereby significantly enhancing the crosslinking density and resilience of the polymer matrix itself; in addition, it can also form a strong and flexible connection interface between the filler and the matrix, optimizing stress transmission, so that while achieving high thermal conductivity of the thermally conductive silicone pad, it can still obtain high compression resilience.

[0013] Furthermore, the viscosity of the vinyl silicone oil is 50–100 mPa·s, and the vinyl content is 0.15–0.30 wt%.

[0014] Furthermore, the viscosity of the hydrogen-containing silicone oil is 20–60 mPa·s, and the active hydrogen content is 0.1–0.3 wt%.

[0015] Furthermore, the catalyst is a platinum catalyst.

[0016] Furthermore, the small-particle-size spherical alumina refers to spherical alumina with a particle size of 0.5 to 5 μm.

[0017] Secondly, the present invention provides a method for preparing the resilient thermally conductive silicone pad as described above, comprising the following steps: Step S1: Preparation of graphene slurry Mix 5-15 parts of dimethyl silicone oil and 15-25 parts of monocrystalline alumina evenly, then add 1-3 parts of silane coupling agent, 1-5 parts of graphene and 0.1-1 parts of chelating dispersant in sequence. After mixing thoroughly, add 15-25 parts of monocrystalline alumina and stir until evenly mixed to obtain graphene slurry. Step S2: Processing large-particle-size thermally conductive fillers 100 parts of large-particle-size thermally conductive particles are thoroughly mixed with 3 to 5 parts of surface treatment agent, and then 1 to 3 parts by weight of thermally conductive gel are added. The mixture is reacted at 80 to 100°C for 15 to 30 minutes and then cooled to obtain the treated large-particle-size thermally conductive filler. Step S3: Prepare a resilient thermally conductive silicone pad Vinyl silicone oil, platinum catalyst, hydrogen-containing silicone oil, and small-particle-size spherical alumina are mixed evenly to obtain a basic mixture. The graphene slurry prepared in step S1 is added to the basic mixture, and the mixture is thoroughly mixed for 30-60 minutes and then vacuumed. Then, the treated large-particle-size thermally conductive filler prepared in step S2 is added, and the mixture is mixed evenly. The mixture is then poured into a mold and cured at 100-150°C for 20-40 minutes to obtain the resilient thermally conductive silicone pad.

[0018] Compared with the prior art, the present invention has the following beneficial effects: I. This invention constructs a highly efficient thermally conductive network using graphene, combining a mixture of large-particle-size spherical aluminum nitride and spherical alumina with small-particle-size spherical alumina, enabling the gasket's thermal conductivity to reach over 10 W / (m·K). Simultaneously, through the enhancement of the cross-linked network by chelating dispersants, the elastic coating treatment of the surface of large-particle-size thermally conductive fillers, and the synergistic effect of graphene, the gasket is endowed with excellent resilience. The compression rebound rate at room temperature and 50°C after 2 hours can reach over 30% and 35% respectively, far exceeding that of conventional high-filler gaskets (typically <10%), achieving an excellent balance between high thermal conductivity and high resilience. Second, the high resilience of the gasket can effectively compensate for the gap fluctuations of the heat dissipation interface caused by factors such as vibration and thermal cycling, avoid "thermal runaway" caused by poor contact, significantly improve the long-term heat dissipation reliability under complex working conditions, and have strong dynamic adaptability and high reliability. Third, the present invention adopts a stepwise method of slurry preparation and filler treatment to ensure the uniform distribution and stable presence of key functional components (graphene, chelating dispersant, and elastic coating layer of thermally conductive filler) in the final product, thereby ensuring the consistency and repeatability of product performance, controllable process, and stable performance. Fourth, the thermally conductive pad of the present invention has a certain surface adhesion, which makes it easy to install and position, and it is not easy to fall off, thereby improving assembly efficiency and yield, and having good workability. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0020] raw material Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products. Specifically: Vinyl silicone oil: viscosity 50-100 mPa·s, vinyl content 0.15-0.30 wt%.

[0021] Hydrogen-containing silicone oil: viscosity 20-60 mPa·s, active hydrogen content 0.1-0.3 wt%.

[0022] Small-diameter spherical alumina: average particle size 0.5–5 μm.

[0023] Single crystal alumina: CDHL-20 from Danyang Yunhui Electronics Co., Ltd., with an average particle size of 20 μm.

[0024] Graphene: Multilayer graphene powder, ≤10 layers, sheet diameter ≤10 μm, specific surface area 180~280 m² 2 / g.

[0025] Large-diameter thermally conductive particles: composed of spherical aluminum nitride and spherical aluminum oxide with an average particle size of 100-150 μm in a 1:1 mass ratio.

[0026] Chelating dispersant: Dongguan Jia Hong Goon203.

[0027] Surface treatment agent: Guangzhou Chenxi CX-5569.

[0028] Thermal conductive gel: Guangzhou Chenxi CX-3936 high-resilience silicone resin gel.

[0029] Example 1 Step 1: Preparation of graphene slurry Mix 10 parts of dimethyl silicone oil with 20 parts of single-crystal alumina evenly, then add 2 parts of silane coupling agent KH-550, 3 parts of graphene and 0.5 parts of chelating dispersant. After mixing thoroughly, add 20 parts of single-crystal alumina and stir until evenly mixed to obtain a fine and smooth black paste-like graphene slurry.

[0030] Step 2: Treatment of large-particle-size thermally conductive fillers Mix 100 parts of large-diameter thermally conductive particles with 4 parts of surface treatment agent thoroughly, then add 2 parts of thermally conductive gel, heat to 90℃ and react for 20 minutes, then let cool naturally before use.

[0031] Step 3: Preparation of the resilient thermal pad Raw materials: 100 parts vinyl silicone oil, 0.2 parts platinum catalyst, 5 parts hydrogen-containing silicone oil, 100 small-particle-size spherical alumina, 10 parts graphene slurry (obtained in step 1), and 600 parts large-particle-size thermally conductive filler (obtained in step 2).

[0032] The vinyl silicone oil, hydrogen-containing silicone oil, platinum catalyst, and small-particle-size spherical alumina were mixed evenly in a mixing tank. Then, graphene slurry was added, and the mixture was vacuumed and mixed for 50 minutes. Next, large-particle-size thermally conductive filler was added and mixed evenly. The mixture was then cured at 120°C for 30 minutes to prepare a 2 mm thick thermally conductive pad.

[0033] Example 2 Unlike Example 1, this example includes 0.5 parts catalyst, 10 parts hydrogen-containing silicone oil, 300 parts small-particle-size spherical alumina, 30 parts graphene slurry, and 1000 parts large-particle-size thermally conductive filler. Everything else is the same as in Example 1 and will not be repeated here.

[0034] Example 3 Unlike Example 1, this example includes 0.3 parts catalyst, 10 parts hydrogen-containing silicone oil, 200 parts small-particle-size spherical alumina, 20 parts graphene slurry, and 800 parts large-particle-size thermally conductive filler. Everything else is the same as in Example 1 and will not be repeated here.

[0035] Example 4 Unlike Example 3, this example includes 15 parts of graphene slurry. Everything else is the same as in Example 3 and will not be repeated here.

[0036] Comparative Example 1 Unlike Example 1, in the preparation of graphene slurry in this comparative example, an equal amount of single-crystal alumina CDHL-20 was used to replace graphene. The remaining formulation steps are the same as in Example 1 and will not be repeated here.

[0037] Comparative Example 2 Unlike Example 2, in the preparation process of the large particle size thermally conductive filler in this comparative example, the amount of thermally conductive gel added is 0, and the remaining formulation steps are the same as in Example 2, and will not be repeated here.

[0038] Comparative Example 3 Unlike Example 3, in the preparation of graphene slurry in this comparative example, an equal amount of single-crystal alumina CDHL-20 was used to replace graphene. In the preparation of large-particle-size thermally conductive filler, the amount of thermally conductive gel added was 0. The remaining formulation steps were the same as in Example 3 and will not be repeated here.

[0039] Comparative Example 4 Unlike Example 4, the amount of chelating dispersant added in the preparation process of the graphene slurry in this comparative example is 0, and the remaining formulation steps are the same as in Example 4, and will not be repeated here.

[0040] The following tests were performed on the thermal pads of Examples 1-4 and Comparative Examples 1-4: Compression resilience test: The prepared 2 mm thick gasket sample was compressed to a thickness of 1 mm at room temperature (25℃) and held for 30 minutes, then the pressure was removed. The thickness of the sample was measured after being left to stand freely at room temperature and at a constant temperature of 50℃ for 2 hours, and the compression resilience was calculated. The formula for calculating the compression resilience is: Compression rebound rate = (T) 放 -T0) / T0×100%; Where T0 is the compression thickness, which is 1 mm in this embodiment; T 放 The thickness is the thickness after being left to stand freely for 2 hours at room temperature or a constant temperature of 50°C.

[0041] Thermal conductivity test: The test was conducted using a thermal conductivity meter in accordance with the ASTM D5470 standard.

[0042] The test results are shown in Table 1: Table 1

[0043] As can be seen from the data in Table 1: The high thermal conductivity silicone pads prepared in Examples 1 to 4 of this invention, while maintaining excellent thermal conductivity (thermal conductivity ≥9.86 W / m·K, of which Examples 2 to 4 exceed 10 W / m·K), all exhibit outstanding compression resilience (compression resilience of 33% to 45% at room temperature and 35% to 48% at 50℃), achieving a balance between high thermal conductivity and high resilience.

[0044] Comparative Examples 1, 2, and 3 lacked "graphene," "thermal conductive gel treatment," or both, respectively. Although their resilience (22%–27%) was better than that of traditional high-filler gaskets, it was significantly lower than that of the embodiments of the present invention. This demonstrates that the introduction of graphene and the elasticization treatment of large-particle fillers both make significant contributions to the synergistic improvement of resilience.

[0045] Comparative Example 4, lacking only the chelating dispersant, exhibited a drastic deterioration in resilience (only 7.3% at room temperature), comparable to conventional high-fill gaskets, while thermal conductivity remained unaffected. This comparative result fully demonstrates that the chelating dispersant with a telechelic structure is crucial for constructing a high-strength elastic network. Its core role in achieving the high resilience of this invention by increasing cross-linking points to form a three-dimensional network far surpasses that of ordinary dispersants.

[0046] In summary, this invention, through the synergistic design of graphene, chelated dispersants, and treated large-particle-size thermally conductive fillers, successfully achieves a balance between high thermal conductivity and high resilience, providing a reliable solution for heat dissipation of electronic devices in complex environments.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A resilient thermally conductive silicone pad, characterized in that, By weight, it includes the following ingredients: 100 parts vinyl silicone oil; 600-1000 parts of treated large-particle-size thermally conductive filler; 100-300 parts of small-particle-size spherical alumina; 10-30 parts of graphene slurry; 5-10 parts of hydrogen-containing silicone oil; Catalyst 0.2 to 0.5 parts.

2. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The preparation of the treated large-particle-size thermally conductive filler includes: thoroughly mixing large-particle-size thermally conductive particles with a surface treatment agent, then adding thermally conductive gel, reacting at 80-100°C for 15-30 minutes, and obtaining the treated large-particle-size thermally conductive filler after cooling.

3. The resilient thermally conductive silicone pad according to claim 2, characterized in that, The large-diameter thermally conductive particles are a mixture of spherical aluminum nitride and spherical aluminum oxide with an average particle size of 100-150 μm in a 1:1 mass ratio; the surface treatment agent is a long-chain alkyl silane; and the thermally conductive gel is a high-resilience silicone resin gel.

4. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The graphene slurry is prepared from the following raw materials in parts by weight: 5-15 parts dimethyl silicone oil, 30-50 parts single-crystal alumina, 1-3 parts silane coupling agent, 1-5 parts graphene, and 0.1-1 parts chelating dispersant.

5. The resilient thermally conductive silicone pad according to claim 4, characterized in that, The dimethyl silicone oil has a viscosity of 50–100 mPa·s; the single-crystal alumina has an average particle size of 15–25 μm; the graphene is a multilayer graphene powder with ≤10 layers, a sheet diameter ≤10 μm, and a specific surface area of ​​180–280 m². 2 / g, wherein the chelating dispersant is a compound having a telechelic structure.

6. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The vinyl silicone oil has a viscosity of 50–100 mPa·s and a vinyl content of 0.15–0.30 wt%.

7. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The hydrogen-containing silicone oil has a viscosity of 20–60 mPa·s and an active hydrogen content of 0.1–0.3 wt%.

8. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The catalyst is a platinum catalyst.

9. The resilient thermally conductive silicone pad according to claim 1, characterized in that, The small-particle-size spherical alumina refers to spherical alumina with a particle size of 0.5 to 5 μm.

10. The method for preparing the resilient thermally conductive silicone pad according to claims 1 to 9, characterized in that, Includes the following steps: Step S1: Preparation of graphene slurry Mix 5-15 parts of dimethyl silicone oil and 15-25 parts of monocrystalline alumina evenly, then add 1-3 parts of silane coupling agent, 1-5 parts of graphene and 0.1-1 parts of chelating dispersant in sequence. After mixing thoroughly, add 15-25 parts of monocrystalline alumina and stir until evenly mixed to obtain graphene slurry. Step S2: Processing large-particle-size thermally conductive fillers 100 parts of large-particle-size thermally conductive particles are thoroughly mixed with 3 to 5 parts of surface treatment agent, and then 1 to 3 parts by weight of thermally conductive gel are added. The mixture is reacted at 80 to 100°C for 15 to 30 minutes and then cooled to obtain the treated large-particle-size thermally conductive filler. Step S3: Prepare a resilient thermally conductive silicone pad Vinyl silicone oil, platinum catalyst, hydrogen-containing silicone oil, and small-particle-size spherical alumina are mixed evenly to obtain a basic mixture. The graphene slurry prepared in step S1 is added to the basic mixture, and the mixture is thoroughly mixed for 30-60 minutes and then vacuumed. Then, the treated large-particle-size thermally conductive filler prepared in step S2 is added, and the mixture is mixed evenly. The mixture is then poured into a mold and cured at 100-150°C for 20-40 minutes to obtain the resilient thermally conductive silicone pad.

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