Wave-absorbing heat-conducting gasket and preparation method thereof

Abstract

The invention relates to the technical field of composite materials, in particular to a wave-absorbing heat-conducting gasket and a preparation method thereof. The heat-conducting wave-absorbing silicone oil composition comprises 3-10 parts of vinyl silicone oil, 20-45 parts of a heat-conducting filler and 45-70 parts of a wave-absorbing filler, the heat-conducting filler comprises a first heat-conducting filler with a particle size of 80-120 [mu] m and a second heat-conducting filler with a particle size of 8-12 [mu] m, and a weight ratio of the first heat-conducting filler to the second heat-conducting filler is 20: (10-16). The heat conductivity of the prepared gasket is higher than 3 W / (m.K), the electromagnetic shielding performance reflectivity is smaller than-5 dB, and no condensate is generated when the gasket is baked under the condition of 150 DEG C.

Description

Technical Field

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

[0002] As the power and integration of electronic devices increase, the power density within the system continues to rise. This generates significant amounts of waste heat during device operation, often requiring the use of thermally conductive silicone rubber to transfer this excess heat to the external, cooler environment to prevent overheating. At the same time, electromagnetic pollution and information leakage from electronic devices are becoming increasingly serious. Many electronic components emit electromagnetic radiation during operation, causing electromagnetic interference to surrounding equipment. Because electronic devices are confined within tight spaces, thermally conductive absorbent materials that combine heat conduction and absorption have become the most effective means of addressing the challenges of efficient heat dissipation and electromagnetic compatibility. Therefore, integrating absorbent and thermally conductive materials into the same gasket can simplify design, reduce costs, and improve overall performance. To address these issues, products such as silicone thermally conductive absorbent gaskets and coatings have emerged on the market, aiming to enhance the heat dissipation capabilities of electronic devices while reducing electromagnetic interference. However, traditional silicone thermally conductive absorbent materials combine thermally conductive fillers and absorbents within a silicone matrix to achieve both heat conduction and electromagnetic wave absorption. Since there is a limit to the filling capacity of fillers in polymer matrices such as rubber, the amount of thermal conductive filler and wave-absorbing filler added is in a trade-off relationship, and the same is true for performance, making it difficult to achieve a synergistic improvement in the two properties.

[0003] Chinese invention patent CN116622242A discloses a high-thermal-conductivity, wave-absorbing gasket, its preparation method, and application. The raw materials include silicone oil, a thermally conductive filler, and a wave-absorbing filler. The thermally conductive filler includes first thermally conductive particles with a particle size of 20-150 μm, second thermally conductive particles with a particle size of 1-50 μm, and third thermally conductive particles with a particle size of 0.1-20 μm. The viscosity of the silicone oil is 50-10,000 m·Pa. The high-thermal-conductivity, wave-absorbing gasket prepared in this invention utilizes a combination of multiple wave-absorbing fillers and thermally conductive particles in specific proportions and particle sizes. While the thermal conductivity reaches 7-7.5 W / (m·K), certain electromagnetic compatibility issues remain. Summary of the Invention

[0004] The first aspect of the present invention provides a wave-absorbing heat-conducting gasket, which comprises, by weight, 5-8 parts of vinyl silicone oil, 30-45 parts of thermally conductive filler, and 55-60 parts of wave-absorbing filler, wherein the thermally conductive filler comprises a first thermally conductive filler with a particle size of 80-120 μm and a second thermally conductive filler with a particle size of 8-12 μm.

[0005] Preferably, the first thermally conductive filler may have the following particle sizes: 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, and 115 μm.

[0006] Preferably, the second thermally conductive filler may have the following particle sizes: 8.5 μm, 9.0 μm, 9.5 μm, 10.0 μm, 10.5 μm, 11.0 μm, and 11.5 μm.

[0007] The weight ratio of the first thermally conductive filler to the second thermally conductive filler is 20:(10-16).

[0008] Preferably, the weight ratio of the first thermally conductive filler to the second thermally conductive filler is 20:(10-15).

[0009] Further preferably, the weight ratio of the first thermally conductive filler to the second thermally conductive filler is 20:13.

[0010] The thermally conductive filler further includes a third thermally conductive filler with a particle size of 0.8-1.5 μm, and the weight ratio of the first thermally conductive filler, the second thermally conductive filler and the third thermally conductive filler is 20: (10-16): (3-8). Preferably, the third thermally conductive filler may have the following particle sizes: 0.85 μm, 0.9 μm, 0.95 μm, 1 μm, 1.2 μm, 1.3 μm, 1.4 μm, and 1.05 μm.

[0011] Preferably, the weight ratio of the first thermally conductive filler, the second thermally conductive filler and the third thermally conductive filler is 20: (10-15): (3-5).

[0012] Further preferably, the weight ratio of the first thermally conductive filler, the second thermally conductive filler and the third thermally conductive filler is 20:13:5.

[0013] The weight ratio of the thermal conductive filler to the wave absorbing filler is 1:(1.2-2).

[0014] Preferably, the weight ratio of the thermally conductive filler to the wave-absorbing filler is 1:(1.4-1.9).

[0015] Further preferably, the weight ratio of the thermally conductive filler to the wave-absorbing filler is 38:55.

[0016] Existing silicone thermally conductive and absorbing materials have limited filler loading within polymer matrices like rubber, making it difficult to achieve a synergistic improvement in both properties. This study found that a weight ratio of 1:1.2-2 for thermally conductive and absorbing fillers can simultaneously improve both thermal conductivity and absorption. This is likely due to the higher content of carbon-based absorbing fillers, which improves compatibility with silicone. Further research has found that using thermally conductive fillers of varying particle sizes can reduce the free matter in the material, thereby improving thermal conductivity. In particular, using fillers of the same type with different particle sizes further improves dispersibility between the systems.

[0017] The components further include: at least one of a treating agent, hydrogen-containing silicone oil, an inhibitor and a catalyst.

[0018] The weight ratio of the treating agent, hydrogen-containing silicone oil, inhibitor and catalyst is 0.4: (0.1-0.5): (0.001-0.015): (0.05-0.15).

[0019] Preferably, the weight ratio of the treating agent, hydrogenated silicone oil, inhibitor and catalyst is 0.4:(0.2-0.4):(0.001-0.01):(0.05-0.1).

[0020] The treatment agent includes at least one of a silane coupling agent, a phthalate coupling agent, and an aluminate coupling agent.

[0021] Preferably, the treating agent includes a silane coupling agent.

[0022] More preferably, the treating agent includes dodecyltrimethoxysilane.

[0023] The inhibitor includes butynylcyclohexanol or acetylene alcohol.

[0024] The catalyst includes a platinum catalyst.

[0025] The thermally conductive filler includes at least one of aluminum oxide, zinc oxide, boron nitride, aluminum nitride, aluminum powder, silver powder, graphene, and carbon nanotubes.

[0026] Preferably, the thermally conductive filler comprises aluminum oxide.

[0027] The wave-absorbing filler includes at least one of graphite, graphene, ferrite, cobalt-iron alloy, carbonyl iron powder, carbon nanotubes, and silicon carbide.

[0028] Preferably, the wave-absorbing filler comprises carbonyl iron powder.

[0029] The particle size of the wave-absorbing filler is 1-10 μm.

[0030] Preferably, the particle size of the wave-absorbing filler is 1-5 μm.

[0031] More preferably, the absorbing filler may have the following particle sizes: 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, and 4.5 μm.

[0032] The viscosity of the vinyl silicone oil at 25° C. is 500-1000 cps, and the viscosity of the hydrogenated silicone oil at 25° C. is 50-400 cps.

[0033] Preferably, the viscosity of the vinyl silicone oil at 25° C. is 700-1000 cps, and the viscosity of the hydrogenated silicone oil at 25° C. is 100-400 cps.

[0034] A second aspect of the present invention provides a method for preparing a wave-absorbing thermally conductive gasket, comprising the following steps: fully mixing all components; evacuating the components; and pressing the components into a desired shape and size to form a wave-absorbing thermally conductive gasket.

[0035] Beneficial effects 1. By limiting the thermal conductive filler to include a first thermal conductive filler with a particle size of 80-120 μm and a second thermal conductive filler with a particle size of 8-12 μm, and the weight ratio of the first thermal conductive filler to the second thermal conductive filler is 20: (10-16), the thermal conductivity and wave absorption performance can be improved at the same time.

[0036] 2. By limiting the weight ratio of thermal conductive filler to wave absorbing filler to 1: (1.2-2), the thermal conductivity of the material is higher than 2.5W / (m·K) and the electromagnetic shielding performance reflectivity is less than -2dB.

[0037] 3. By limiting the weight ratio of the first thermally conductive filler, the second thermally conductive filler and the third thermally conductive filler to 20: (10-15): (3-5), the thermal conductivity of the material is higher than 3W / (m·K) and the electromagnetic shielding performance reflectivity is less than -5dB.

[0038] 4. By limiting the weight ratio of thermal conductive filler to wave absorbing filler to 1: (1.4-1.9), the density of the gasket can be effectively reduced while maintaining the thermal conductivity and wave absorbing properties.

[0039] 5. By limiting the weight ratio of the treating agent, hydrogenated silicone oil, inhibitor and catalyst to 0.4: (0.1-0.5): (0.001-0.015): (0.05-0.15), and the viscosity of the hydrogenated silicone oil at 25°C is 50-400 cps, the volatility of the gasket can be reduced, and no condensate is produced when baked at 150°C.

[0040] 6. The oil mist resistance of the gasket can be further improved by limiting the weight ratio of the treating agent, hydrogenated silicone oil, inhibitor and catalyst to 0.4: (0.2-0.4): (0.001-0.01): (0.05-0.1). DETAILED DESCRIPTION

[0041] Examples 1-4 A wave-absorbing heat-conducting gasket, the components of which are shown in Table 1 in parts by weight: Table 1

[0042] Among them, silicone oil A model: VS-1000M, Jingri silicone.

[0043] A method for preparing a wave-absorbing heat-conducting gasket comprises the following steps: 1. Gradually add vinyl silicone oil, thermal conductive filler, wave absorbing filler, treatment agent, inhibitor, hydrogen-containing silicone oil and catalyst into the blender and stir at 25℃ for 1 hour; 2. Vacuum at 120℃ for 1 hour to remove bubbles and excess water from the mixture; 3. Use a calender to press it into the required shape and size to form a wave-absorbing and heat-conducting gasket.

[0044] Comparative Example 1 A wave-absorbing heat-conducting gasket, the components of which are shown in Table 2 in parts by weight: Table 2

[0045] A method for preparing a wave-absorbing heat-conducting gasket comprises the following steps: 1. Gradually add vinyl silicone oil, thermal conductive filler, wave absorbing filler, treatment agent, inhibitor, hydrogen-containing silicone oil and catalyst into the blender and stir at 25℃ for 1 hour; 2. Vacuum at 120℃ for 1 hour to remove bubbles and excess water from the mixture; 3. Use a calender to press it into the required shape and size to form a wave-absorbing and heat-conducting gasket.

[0046] Performance testing methods The wave-absorbing and heat-conducting gaskets (60 mm×60 mm×2 mm) prepared in the examples and comparative examples were subjected to the following performance tests, and the test data are listed in Table 3.

[0047] Hardness (ASTM D2240) unit: Shore OO Thermal conductivity (ASTM D5470) unit: W / m K Density (ASTM D792) Unit: g / cm 3 Oil mist: ASTM D595 Performance test data Table 3

[0048] As can be seen from Table 3, Examples 1 to 4 are all implemented according to the characteristics of the present technical solution, and the prepared single-component thermal conductive and wave absorbing materials have good thermal conductivity, wave absorbing properties and oil mist resistance.

Claims

1. A wave-absorbing and heat-conducting gasket, characterized in that: In parts by weight, the components include: 5-8 parts of vinyl silicone oil, 30-45 parts of thermally conductive filler and 55-60 parts of wave-absorbing filler. The thermally conductive filler includes a first thermally conductive filler with a particle size of 80-120 μm and a second thermally conductive filler with a particle size of 8-12 μm. The weight ratio of the first thermally conductive filler to the second thermally conductive filler is 20:(10-16).

2. The wave absorbing and heat conducting gasket according to claim 1, characterized in that: The thermally conductive filler further includes a third thermally conductive filler with a particle size of 0.8-1.5 μm, and the weight ratio of the first thermally conductive filler, the second thermally conductive filler and the third thermally conductive filler is 20: (10-16): (3-8).

3. The wave absorbing and heat conducting gasket according to claim 1 or 2, characterized in that: The weight ratio of the thermal conductive filler to the wave absorbing filler is 1:(1.2-2).

4. The wave absorbing and heat conducting gasket according to claim 3, characterized in that: The components further include: at least one of a treating agent, hydrogen-containing silicone oil, an inhibitor and a catalyst.

5. The wave absorbing and heat conducting gasket according to claim 4, characterized in that: The weight ratio of the treating agent, hydrogen-containing silicone oil, inhibitor and catalyst is 0.4: (0.1-0.5): (0.001-0.015): (0.05-0.15).

6. The wave absorbing and heat conducting gasket according to claim 1 or 5, characterized in that: The thermally conductive filler includes at least one of aluminum oxide, zinc oxide, boron nitride, aluminum nitride, aluminum powder, silver powder, graphene, and carbon nanotubes.

7. The wave absorbing and heat conducting gasket according to claim 6, characterized in that: The wave-absorbing filler includes at least one of graphite, graphene, ferrite, cobalt-iron alloy, carbonyl iron powder, carbon nanotubes, and silicon carbide.

8. The wave absorbing and heat conducting gasket according to claim 7, characterized in that: The particle size of the wave-absorbing filler is 1-10 μm.

9. The wave absorbing and heat conducting gasket according to claim 4, characterized in that: The viscosity of the vinyl silicone oil at 25° C. is 500-1000 cps, and the viscosity of the hydrogenated silicone oil at 25° C. is 50-400 cps.

10. A method for preparing the wave-absorbing and heat-conducting gasket according to any one of claims 1 to 9, characterized in that: The following steps are involved: All components are mixed thoroughly; vacuumed; and pressed into the desired shape and size to form a wave absorbing and thermally conductive gasket.

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