An insulating heat-conducting gasket and a method for manufacturing the same

Abstract

The application belongs to the field of heat-conducting materials, and particularly relates to an insulating heat-conducting gasket and a preparation method thereof. The insulating heat-conducting gasket is prepared from the following raw materials by weight: 90-100 parts by weight of vinyl silicone oil, 1-3 parts by weight of hydrogen-containing silicone oil, 0.01-0.03 parts by weight of an inhibitor, 0.1-0.2 parts by weight of a catalyst, and 600-900 parts by weight of modified heat-conducting fillers; wherein the modified heat-conducting fillers are composed of modified carbon fibers, modified carbon nanotubes and base fillers. The insulating heat-conducting gasket has the characteristics of high heat conduction, high insulation and good mechanical properties, and can meet the requirements of practical applications.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of heat-conducting materials, and particularly relates to an insulating heat-conducting gasket and a preparation method thereof. BACKGROUND

[0002] With the vigorous development of electronic information technology, small, high-integration, high-performance electronic devices have become the mainstream of development. These devices will generate significant heat under high-efficiency operation, and if the heat cannot be effectively dissipated, it will cause risks such as circuit failure, component damage, and electrical breakdown, so the demand for thermal management is more urgent.

[0003] Heat-conducting gaskets, as an important component of thermal interface materials, play an important role in them. They can fill the tiny gaps between heat-generating components and heat-dissipating components, expel air, thereby reducing the interface contact thermal resistance and achieving efficient heat conduction. In addition, heat-conducting gaskets can also provide additional functions such as packaging, shock absorption, and insulation. Heat-conducting and insulating gaskets have important applications in the fields of electronics, electric power, automobiles, aerospace, etc., and provide key support for thermal conduction and electrical insulation for devices and systems in these fields.

[0004] In order to further improve the thermal conductivity of thermal interface materials, some researches such as CN106634863A, CN106813226A, CN109354874A, etc. apply super-high thermal-conducting graphene, carbon nanotubes, carbon fibers, etc. as thermal-conducting fillers to heat-conducting gaskets, however, such carbon materials often have certain electrical conductivity, which is extremely detrimental to electronic devices and can easily cause equipment short circuits and dangers. Therefore, how to maintain high thermal conductivity while avoiding the drawbacks of carbon materials is still a research hotspot in the field of thermal interface materials. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides an insulating heat-conducting gasket, which uses a modified thermal-conducting filler composed of modified carbon fibers, modified carbon nanotubes, and basic fillers, which not only ensures the high thermal conductivity of the gasket and effectively conducts heat, but also has the advantages of insulation and good mechanical properties. The present application also provides a preparation method of the above-mentioned insulating heat-conducting gasket.

[0006] An insulating heat-conducting gasket is prepared from the following raw materials in parts by weight:

[0007] 90-100 parts by weight of vinyl silicone oil, 1-3 parts by weight of hydrogen-containing silicone oil, 0.01-0.03 parts by weight of inhibitor, 0.1-0.2 parts by weight of catalyst, and 600-900 parts by weight of modified thermal-conducting filler.

[0008] The existing heat-conducting gaskets are prepared by adding aluminum nitride, aluminum oxide, silicon dioxide, hexagonal boron nitride, diamond and other basic heat-conducting fillers into a polymer matrix, but often have the problem of poor heat-conducting performance. The present application uses a small amount of carbon nanotubes and carbon fibers with excellent mechanical properties and high heat conductivity in combination with the basic heat-conducting fillers to significantly improve the heat conductivity of the gasket, and through modification of the carbon nanotubes and carbon fibers, the adverse effects of their own electrical conductivity are reduced while maintaining their high heat conductivity and high strength.

[0009] Preferably, the modified heat-conducting fillers are composed of 1-2wt% modified carbon fibers, 0.1-0.5wt% modified carbon nanotubes and the rest of the basic fillers.

[0010] The present application first pretreats the carbon fibers with Tween-20 as a dispersant, then coats the carbon fibers with silica sol through interfacial adsorption and forms a silica-coated insulating layer through calcination, which can improve the poor wettability and weak interfacial bonding between the carbon fibers and the matrix, make them orderly arranged in the matrix, effectively improve the high heat conductivity and mechanical properties of the heat-conducting gasket, and also avoid the adverse effects of the electrical conductivity of the carbon fibers.

[0011] Preferably, the preparation method of the modified carbon fibers is as follows:

[0012] 10-15 parts by weight of carbon fibers, 1-5 parts by weight of Tween-20 are added to 80-90 parts by weight of dimethyl sulfoxide and mixed uniformly, then reacted at 50-60℃ for 0.5-2h, then 1-5 parts by weight of silica sol is added and reacted for 2-4h, centrifuged, dried at 80-90℃ for 30-60min, then calcined at 1100-1300℃ under nitrogen protection for 3-5h to obtain the modified carbon fibers.

[0013] The present application can solve the problems of poor dispersibility and compatibility with the matrix, large interfacial thermal resistance and ineffective conduction of carbon nanotubes due to their high aspect ratio and large specific surface area, and the heat-conducting performance of the gasket is not significantly improved. The present application takes advantage of the negative charge on the surface of carbon nanotubes, modifies hexagonal boron nitride with 3-(2-aminoethylamino) propyl methyldimethoxysilane to cover the surface with positive charges, and through electrostatic interaction and chemical bonding, self-assembly occurs between the two, which coats the surface of the carbon nanotubes with a layer of firm insulating heat-conducting filler, not only improving the compatibility and dispersibility with the matrix and further improving the heat-conducting performance, but also reducing the adverse effects of its own electrical conductivity.

[0014] Preferably, the preparation method of the modified carbon nanotubes is as follows:

[0015] The 3-(2-aminoethylamino)propyl methyl dimethoxysilane 0.1-0.5 parts by weight, 35-37 wt% hydrochloric acid 0.01-0.03 parts by weight are added into 20-50 parts by weight of anhydrous ethanol to mix uniformly to obtain a modified liquid; the modified liquid is uniformly sprayed into the hexagonal boron nitride, the weight ratio of the modified liquid to the hexagonal boron nitride is 1:7-10, and dried at 70-80°C for 60-90 min to obtain the surface modified hexagonal boron nitride; 10-20 parts by weight of carbon nanotubes and 3-6 parts by weight of the surface modified hexagonal boron nitride are added into 150-200 parts by weight of methyl sulfoxide to mix uniformly, reacted at 30-35°C for 2-5 h, centrifuged, dried at 80-90°C for 30-60 min, and then calcined at 1500-1600°C under nitrogen protection for 1-3 h to obtain the modified carbon nanotubes.

[0016] Preferably, the base filler is at least one of aluminum nitride, aluminum oxide, silicon dioxide, hexagonal boron nitride, and diamond. Further preferably, the base filler is aluminum nitride.

[0017] Preferably, the inhibitor is any one of acetylenic group cyclic alcohol compounds and alkenyl cyclic siloxane compounds. Further preferably, the inhibitor is 1-ethynylcyclohexanol.

[0018] Preferably, the catalyst is any one of rhodium catalyst, platinum gold catalyst, and palladium catalyst. Further preferably, the catalyst is platinum gold catalyst.

[0019] In a specific embodiment, the vinyl silicone oil has a vinyl content of 0.65% and a viscosity of 1000 mPa.s.

[0020] In a specific embodiment, the hydrogen-containing silicone oil has an end hydrogen content of 0.32% and a viscosity of 500 mPa.s.

[0021] In a specific embodiment, the carbon fiber is pitch-based carbon fiber, has a diameter of 7 μm, and a length of 200 μm.

[0022] In a specific embodiment, the silica sol has a solid content of 50 wt%, a pH of 9.5-10.5, and an average particle size of 80-120 nm.

[0023] In a specific embodiment, the carbon nanotube is a single-walled carbon nanotube that is not modified, aminated, or carboxylated, has a tube diameter of 1-5 nm, and a length of 20-50 μm.

[0024] In a specific embodiment, the hexagonal boron nitride is 100 nm hexagonal boron nitride.

[0025] In a specific embodiment, the aluminum nitride is 30 μm aluminum nitride.

[0026] In the specific embodiment, the platinum content of the platinum catalyst is 3000 ppm.

[0027] The application also provides a preparation method of the insulating and heat-conducting gasket, comprising the following steps:

[0028] The 90-100 parts by weight of vinyl silicone oil, 1-3 parts by weight of hydrogen-containing silicone oil, 0.01-0.03 parts by weight of inhibitor, and 0.1-0.2 parts by weight of catalyst are added into a kneader for stirring until uniformly mixed; then 600-900 parts by weight of modified heat-conducting filler is added for stirring until uniformly mixed; vacuum extraction, calendering molding; heating and curing at 120-130 DEG C, cooling, to obtain the insulating and heat-conducting gasket.

[0029] The application has the following advantages:

[0030] The carbon nanotubes and carbon fibers with excellent mechanical and heat-conducting properties are combined with the basic heat-conducting filler, so that the heat-conducting property of the gasket is significantly improved, and the carbon nanotubes and carbon fibers are modified to reduce the adverse effects caused by their own electrical conductivity while maintaining their high heat-conducting and high-strength properties. DETAILED DESCRIPTION

[0031] The above summary of the application will be further described in detail in combination with the specific embodiments, but it should not be understood that the scope of the above subject matter of the application is limited to the following examples.

[0032] Example 1

[0033] A preparation method of an insulating and heat-conducting gasket, comprising the following steps:

[0034] The 98 parts by weight of vinyl silicone oil, 2 parts by weight of hydrogen-containing silicone oil, 0.02 parts by weight of inhibitor 1-ethynylcyclohexanol, and 0.18 parts by weight of platinum catalyst are added into a kneader for stirring until uniformly mixed; then 700 parts by weight of modified heat-conducting filler is added for stirring until uniformly mixed; vacuum extraction, calendering molding; heating and curing at 125 DEG C, cooling, to obtain the insulating and heat-conducting gasket.

[0035] The modified heat-conducting filler is composed of 1.6 wt% of modified carbon fiber, 0.4 wt% of modified carbon nanotube, and the rest of aluminum nitride.

[0036] The preparation method of the modified carbon fiber is as follows:

[0037] The 12 parts by weight of carbon fiber and 3 parts by weight of Tween-20 are added into 82 parts by weight of dimethyl sulfoxide for mixing until uniformly mixed, and then reacted at 55 DEG C for 1 h; then 3 parts by weight of silica sol is added for further reaction for 2.5 h; centrifugation, drying at 85 DEG C for 50 min, and then calcining at 1250 DEG C under nitrogen protection for 3.5 h to obtain the modified carbon fiber.

[0038] The preparation method of the modified treatment carbon nanotube is as follows:

[0039] 0.25 parts by weight of 3-(2-aminoethylamino) propyl methyldimethoxysilane, 0.012 parts by weight of 36wt% hydrochloric acid are added into 30 parts by weight of anhydrous ethanol to mix uniformly to obtain a modification liquid; the modification liquid is uniformly sprayed into hexagonal boron nitride, the weight ratio of the modification liquid to the hexagonal boron nitride is 1:8, and the mixture is dried at 78℃ for 80min to obtain surface modified hexagonal boron nitride; 15 parts by weight of carbon nanotubes and 5 parts by weight of surface modified hexagonal boron nitride are added into 180 parts by weight of methyl sulfoxide to mix uniformly, and the mixture is reacted at 32℃ for 2.5h, centrifuged, dried at 85℃ for 50min, and then calcined at 1550℃ under nitrogen protection for 1.5h to obtain the modified treatment carbon nanotube.

[0040] Example 2

[0041] A preparation method of an insulating and heat-conducting gasket, comprising the following steps:

[0042] 98 parts by weight of vinyl silicone oil, 2 parts by weight of hydrogen-containing silicone oil, 0.02 parts by weight of inhibitor 1-ethynylcyclohexanol, and 0.18 parts by weight of platinum gold catalyst are added into a kneader to stir until uniformly mixed; then 700 parts by weight of modified heat-conducting filler is added to stir until uniformly mixed; vacuum extraction, calendering molding; heating and curing at 125℃, cooling, to obtain the insulating and heat-conducting gasket.

[0043] The modified heat-conducting filler is composed of 1.6wt% modified treatment carbon fiber, 0.4wt% carbon nanotube, and the rest is aluminum nitride.

[0044] The preparation method of the modified treatment carbon fiber is as follows:

[0045] 12 parts by weight of carbon fiber and 3 parts by weight of Tween-20 are added into 82 parts by weight of dimethyl sulfoxide to mix uniformly, and the mixture is reacted at 55℃ for 1h, then 3 parts by weight of silica sol is added to continue to react for 2.5h, centrifuged, dried at 85℃ for 50min, and then calcined at 1250℃ under nitrogen protection for 3.5h to obtain the modified treatment carbon fiber.

[0046] Example 3

[0047] A preparation method of an insulating and heat-conducting gasket, comprising the following steps:

[0048] 98 parts by weight of vinyl silicone oil, 2 parts by weight of hydrogen-containing silicone oil, 0.02 parts by weight of inhibitor 1-ethynylcyclohexanol, and 0.18 parts by weight of platinum gold catalyst were added into a kneader and stirred until uniformly mixed; then 700 parts by weight of modified heat-conductive filler was added and stirred until uniformly mixed; vacuum extraction was performed, and calender molding was performed; heating and curing were performed at 125°C, and cooling was performed, to obtain the insulating heat-conductive gasket.

[0049] The modified heat-conductive filler is composed of 2wt% of modified carbon fiber and the balance of aluminum nitride.

[0050] The preparation method of the modified carbon fiber is as follows:

[0051] 12 parts by weight of carbon fiber and 3 parts by weight of Tween-20 were added into 82 parts by weight of dimethyl sulfoxide and uniformly mixed, and then reacted at 55°C for 1h; 3 parts by weight of silica sol was then added and reacted for 2.5h; centrifugation was performed, and drying was performed at 85°C for 50min; and calcination was performed at 1250°C under nitrogen protection for 3.5h, to obtain the modified carbon fiber.

[0052] Example 4

[0053] A preparation method of an insulating heat-conductive gasket, comprising the following steps:

[0054] 98 parts by weight of vinyl silicone oil, 2 parts by weight of hydrogen-containing silicone oil, 0.02 parts by weight of inhibitor 1-ethynylcyclohexanol, and 0.18 parts by weight of platinum gold catalyst were added into a kneader and stirred until uniformly mixed; then 700 parts by weight of modified heat-conductive filler was added and stirred until uniformly mixed; vacuum extraction was performed, and calender molding was performed; heating and curing were performed at 125°C, and cooling was performed, to obtain the insulating heat-conductive gasket. The modified heat-conductive filler is composed of 2wt% of carbon fiber and the balance of aluminum nitride.

[0055] Test Example 1

[0056] The tensile strength of the heat-conductive gasket of the above examples was tested by using a universal testing machine according to the method of ASTM D412 standard.

[0057] Table 1. Tensile strength of heat-conductive gasket

[0058] Tensile strength, MPa Example 1 0.90 Example 3 0.78

[0059] Test Example 2

[0060] The thermal conductivity of the heat-conductive gasket of the above examples was tested by using a heat-conductivity tester according to the method of ASTM D5470 standard. The withstand voltage of the heat-conductive gasket of the above examples was tested by using a withstand voltage tester according to the method of ASTM D149 standard.

[0061] Table 2. Thermal conductivity and withstand voltage of heat-conductive gasket

[0062] Thermal conductivity, W / (m-k) Breakdown voltage, V / cm Example 1 5.8 1100 Example 2 5.1 500 Example 3 3.3 1200 Example 4 2.7 700

[0063] It can be seen that, by adding a small amount of carbon nanotubes and carbon fibers with excellent mechanical properties and high thermal conductivity, and combining with the basic thermal conductive filler, the thermal conductivity of the gasket is significantly improved. Through modification of carbon nanotubes and carbon fibers, the adverse effects of their own electrical conductivity are reduced while maintaining high thermal conductivity and high strength. Compared with Example 4, Example 3 uses modified carbon fibers, which are coated with a silica insulating layer by adsorbing silica sol on the surface of the carbon fibers and calcining. This can improve the poor wettability and weak interfacial bonding between the carbon fibers and the matrix, and make them orderly arranged in the matrix, effectively improving the high thermal conductivity and mechanical properties of the thermal conductive gasket, while having good insulation. Compared with Example 2, Example 1 uses modified carbon nanotubes, which use the feature of negative charge on the surface of carbon nanotubes to modify hexagonal boron nitride with 3-(2-aminoethylamino) propyl methyl dimethoxy silane to cover the surface with positive charge. Through electrostatic interaction and chemical bonding, self-assembly occurs between the two, which can improve the dispersion of carbon nanotubes due to their high aspect ratio and large specific surface area, and the compatibility with the matrix is poor, and there is a large interfacial thermal resistance, which cannot effectively conduct, so the thermal conductivity of the gasket is not significantly improved. This can further improve the thermal conductivity and reduce the adverse effects of its own electrical conductivity.

[0064] The preferred embodiments of the present application are described in detail above. It should be understood that those skilled in the art can make many modifications and changes without creative labor based on the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the prior art according to the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. An insulating thermal gasket, characterized by: The following raw materials are included by weight parts: 90-100 parts by weight of vinyl silicone oil, 1-3 parts by weight of hydrogen-containing silicone oil, 0.01-0.03 parts by weight of inhibitor, 0.1-0.2 parts by weight of catalyst, 600-900 parts by weight of modified thermal conductive filler; The modified thermal conductive filler is composed of 1-2 wt% modified carbon fiber, 0.1-0.5 wt% modified carbon nanotube and the rest of the base filler; The preparation method of the modified carbon fiber is as follows: 10-15 parts by weight of carbon fiber, 1-5 parts by weight of Tween-20 are added to 80-90 parts by weight of dimethyl sulfoxide and mixed uniformly, heated and reacted, then 1-5 parts by weight of silica sol is added for continuous reaction, after centrifugation, drying, and calcination under inert gas protection, the modified carbon fiber is obtained; The preparation method of the modified carbon nanotube is as follows: 0.1-0.5 parts by weight of 3-(2-aminoethylamino) propyl methyldimethoxysilane, 0.01-0.03 parts by weight of hydrochloric acid are added to 20-50 parts by weight of anhydrous ethanol and mixed uniformly to obtain a modification liquid; the modification liquid is uniformly sprayed onto hexagonal boron nitride, dried to obtain surface modified hexagonal boron nitride; the weight ratio of the modification liquid to hexagonal boron nitride is 1:7-10; 10-20 parts by weight of carbon nanotube, 3-6 parts by weight of surface modified hexagonal boron nitride are added to 150-200 parts by weight of methyl sulfoxide and mixed uniformly, heated and reacted, after centrifugation, drying, and calcination under inert gas protection, the modified carbon nanotube is obtained; The base filler is at least one of aluminum nitride, aluminum oxide, silicon dioxide, hexagonal boron nitride, and diamond.

2. The insulating thermal pad of claim 1, wherein: The inhibitor is any one of alkynyl cyclic alcohol compound and alkenyl cyclic siloxane compound.

3. The insulating thermal pad of claim 1, wherein: The catalyst is any one of rhodium catalyst, platinum gold catalyst, and palladium catalyst.

4. The method of making an insulating thermally conductive gasket according to any one of claims 1 to 3, wherein: The following steps are included: The vinyl silicone oil, hydrogen-containing silicone oil, inhibitor, and catalyst are added to a kneader and stirred until uniformly mixed; then the modified thermal conductive filler is added and stirred until uniformly mixed, vacuumized, calendered, cured by heating, cooled, and the insulating thermal conductive gasket is obtained.