A high thermal conductivity silicone thermal conductive gel and preparation method thereof

Abstract

The present application relates to the field of new materials and their application technologies, and specifically to a high thermal conductivity silicone thermal conductive gel and a preparation method thereof. A high thermal conductivity silicone thermal conductive gel, comprising the following components in parts by mass: comprising the following components in parts by mass: 16-20 parts of hydrogenated silicone oil, 28-35 parts of vinyl silicone oil, 0.3-0.6 parts of catalyst, 0.2-0.5 parts of inhibitor, 0.1-0.3 parts of epoxy chain extender, 79-94 parts of composite thermal conductive filler; the composite thermal conductive filler includes modified diamond, aluminum nitride and modified carbon nanotubes. A high thermal conductivity silicone thermal conductive gel of the present application, in view of the low intrinsic thermal conductivity of the thermal conductive filler in the existing thermal conductive gel and the limited degree of interconnection between the thermal conductive filler and the silicone oil, poor stability, and difficulty in applying to heat dissipation of microelectronic devices, makes the intrinsic thermal conductivity of the thermal conductive filler in the thermal conductive gel higher, and strengthens the cross-linking between the thermal conductive filler and the silicone oil, thereby enhancing the aging resistance and stability.

Description

Technical Field

[0001] The present application relates to the technical field of new materials and their applications, and in particular to a highly thermally conductive organic silicone thermally conductive gel and a preparation method thereof. Background Art

[0002] With the development of thermal management and other industries in the large-scale application of new energy vehicle battery packs and the 5G communications industry, higher efficiency has also led to a significant increase in the operating power per unit volume of electronic products, which has brought about serious heat dissipation problems. The heat dissipation generated by electronic components directly leads to increased temperature and thermal stress in electronic equipment, posing a serious threat to the operational reliability of microelectronic devices. There is an extremely fine, uneven air gap between microelectronic devices and heat sinks. Air has a thermal conductivity of only 0.024W / mK, making it a poor conductor of heat. This leads to a very large contact thermal resistance between the electronic components and the heat sink, severely hindering heat transfer and ultimately reducing heat sink efficiency. Therefore, establishing an effective heat conduction channel between the electronic components and the heat sink can significantly reduce the contact thermal resistance and fully utilize the heat sink's function.

[0003] Thermally conductive gel is a thermal interface material with super high adaptability. Compared with thermal gaskets, thermally conductive gel has excellent plasticity and can adapt to various irregular, variable-shaped and uneven heat dissipation interfaces, and its application scenarios are more flexible and varied. The thermally conductive gel currently on the market has the problem of increased hardness during high-temperature heat conduction, which leads to an increase in the contact thermal resistance with the interface during use and a significant reduction in the heat transfer effect. On the other hand, in order to obtain a higher thermal conductivity coefficient, more thermally conductive fillers are generally added to the resin system. However, the intrinsic thermal conductivity of conventional thermally conductive fillers is low, and the degree of interconnection between the thermally conductive fillers and silicone oil is limited, resulting in a low filling rate. Due to the presence of a large amount of silicone oil between the thermally conductive fillers, the aging resistance is poor, and the thermal conductivity performance is not greatly improved. Summary of the Invention

[0004] In view of the low intrinsic thermal conductivity of the thermal conductive filler in the existing thermal conductive gel and the limited degree of interconnection between the thermal conductive filler and the silicone oil, the poor aging stability and the difficulty in applying it to the heat dissipation of microelectronic devices, the present application provides a high thermal conductivity silicone thermal conductive gel and its preparation method.

[0005] In a first aspect, the present application provides a highly thermally conductive silicone thermally conductive gel, which adopts the following technical solution:

[0006] A highly thermally conductive organosilicon thermally conductive gel comprises the following components in parts by weight: 16-20 parts hydrogenated silicone oil, 28-35 parts vinyl silicone oil, 0.3-0.6 parts catalyst, 0.2-0.5 parts inhibitor, 0.1-0.3 parts epoxy chain extender, and 79-94 parts composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond, aluminum nitride, and modified carbon nanotubes.

[0007] By adopting the above technical solution, a highly thermally conductive silicone thermal gel is prepared using a combination of modified diamond, aluminum nitride, and modified carbon nanotubes as composite thermally conductive fillers, with a mixture of vinyl silicone oil, hydrogenated silicone oil, a catalyst, and an epoxy chain extender as the matrix. The epoxy chain extender allows cross-stretching within the silicone oil structure, enhancing crosslinking with the polysiloxane network, thereby improving the stability of the thermal grease, regulating its flow properties, and enhancing the adhesiveness of the thermally conductive silicone gel. Diamond, aluminum nitride, and carbon nanotubes (CNTs) of varying sizes and shapes with higher thermal conductivity were selected as composite thermal fillers. Diamond, as a thermal filler, has higher thermal conductivity than conventional fillers, but diamond powder has poor fluidity and cannot form a good thermal conductivity path. The addition of CNTs not only ensures comparable thermal conductivity as a thermal filler, but also provides an optimal thermal conductivity path for the thermally conductive gel due to their one-dimensional pore structure, resulting in even higher thermal conductivity. Furthermore, the addition of aluminum nitride (AN) particles, which are smaller, allows for the distribution of even smaller particles within the CNTs, ensuring efficient and stable filling of the thermally conductive filler. This improves the uniformity of the internal components, eliminates large pores within individual components of the gel, and enhances the gel's thermal conductivity. This approach fully leverages the influence of the properties of the three components on thermal conductivity, significantly improving the gel's thermal conductivity while maintaining the cost and aging resistance of the gel material.

[0008] In addition, the modification of diamonds and carbon nanotubes in the composite thermally conductive filler reduces the contact thermal resistance between the internal thermally conductive fillers, increases the viscosity and fluidity of the overall composite thermally conductive filler, and improves the thermal conductivity of the thermally conductive gel. Moreover, the modification of the thermally conductive filler increases the number of active functional groups, which can improve the compatibility with silicone oil, allowing the thermally conductive gel to remain stable for a long time without leakage. During high-temperature heat conduction, the interface thermal resistance is smaller, thus avoiding the increase in the hardness of the thermally conductive gel and its adverse effects.

[0009] In a specific embodiment, the modified diamond preparation method comprises the following steps: adding diamond powder to an ethanol solution, ultrasonically grinding, cleaning and drying, adjusting the temperature to 700-750° C. and a low pressure of 100-105 kPa, and depositing in a CO2 atmosphere for 5-8 hours to obtain diamond;

[0010] Take the bisaminosilane coupling agent and add it to anhydrous ethanol, dilute it with distilled water and mix it evenly, hydrolyze it in a water bath at 30-38°C for 30-45 minutes, add the above diamond with stirring, heat it to 60-70°C and react for 3-6 hours, then wash and dry it to obtain the modified diamond.

[0011] By adopting the above technical solution, the diamond powder is vapor deposited to remove impurities while improving the activity of the diamond surface, making it easier to graft and modify. More amino groups are on the diamond surface, which enhances the interface performance between the diamond and the silicone oil matrix and improves the cross-linking performance between the diamond and the matrix silicone oil.

[0012] In a specific embodiment, the mass ratio of the bisaminosilane coupling agent to diamond is (1.2-2.2):1.

[0013] By combining bisaminosilane coupling agent and diamond in a certain range of ratios, the activated diamond surface is grafted with a certain number of amino groups with high activity that can cross-link with the silicone oil matrix. Too much bisaminosilane coupling agent will result in more grafting with epoxy groups, reducing the viscosity and flexible performance of the thermal conductive silicone oil. A small amount of bisaminosilane coupling agent will deteriorate the surface performance of the diamond, affect the interfacial bonding properties with the silicone oil matrix, and affect the stable filling efficiency of the thermal conductive filler.

[0014] In a specific embodiment, the preparation method of the modified carbon nanotubes as hydroxyl-modified carbon nanotubes includes: adding carbon nanotubes to a mixed solution of sulfuric acid and nitric acid, heating to 70-75° C. for reaction, and obtaining modified carbon nanotubes.

[0015] By adopting the above technical solution, the hydroxyl group of carbon nanotubes is modified to enhance the compatibility of carbon nanotubes with modified diamonds, and the interface properties of carbon nanotubes with the silicone oil matrix are reduced. It is also easier to mix with aluminum nitride, thereby reducing the contact thermal resistance between internal thermal conductive fillers and improving the thermal conductivity of the thermal conductive gel.

[0016] In a specific embodiment, the mass ratio of sulfuric acid to nitric acid is 2:(3.2-5.1).

[0017] In a specific embodiment, the mass ratio of the modified diamond, aluminum nitride and modified carbon nanotubes is 1:(5-8):(1:3).

[0018] By adopting the above technical solution, modified diamond, aluminum nitride and modified carbon nanotubes are mixed in a certain proportion range, so that they have better bonding strength with the silicone oil matrix, provide certain viscosity and flow properties, and also make the thermal conductivity optimal within this quality range. Too much modified diamond will increase the hardness of the system, affecting the flexibility of use of the thermal conductive gel, and reduce the bonding strength with the interface, affecting the filling rate, and thus affecting the thermal conductivity. Too much modified carbon nanotubes will make the pores of the system's thermal conductive filler too large, thereby increasing the thermal conductivity rate. However, the thermal conductive gel is easily corroded by the outside world, has weak strength properties, and deteriorates its anti-aging properties.

[0019] In a second aspect, the present application provides a method for preparing a highly thermally conductive silicone thermally conductive gel, using the following technical solution:

[0020] A method for preparing a highly thermally conductive silicone thermally conductive gel comprises the following steps:

[0021] Mix vinyl silicone oil and epoxy chain extender in a double planetary mixer at room temperature for 10-16 minutes, then add the composite thermal conductive filler. Add the composite thermal conductive filler in batches, stir for 5-10 minutes after each addition until uniform, repeat the above steps until all the composite thermal conductive filler is added, raise the temperature to 140-165°C, stir in vacuum, add hydrogen-containing silicone oil, inhibitor, and catalyst, mix at room temperature for 30-40 minutes, and discharge to obtain thermal conductive gel.

[0022] The vacuum stirring is performed at a vacuum degree of -0.04-0.09 MPa and a rotation speed of 50-80 rpm for 1-3 hours.

[0023] The thermally conductive powder is first modified and then the silicone oil system is added in batches. This increases the coverage of the thermally conductive powder particles and has an excellent wetting effect, effectively improving the compatibility between the powder and the thermal conductive gel system. This also enhances the stability and storage resistance of the thermal grease network structure.

[0024] In summary, this application has the following beneficial effects:

[0025] 1. A highly thermally conductive silicone thermal gel is prepared by combining modified diamond, aluminum nitride, and modified carbon nanotubes as composite thermal fillers, with a mixture of vinyl silicone oil, hydrogenated silicone oil, a catalyst, and an epoxy chain extender as the matrix. The epoxy chain extender allows for cross-stretching within the silicone oil structure, enhancing crosslinking with the polysiloxane network, thereby improving the stability of the thermal grease, regulating its flow properties, and enhancing the adhesiveness of the thermally conductive silicone gel. Diamond, aluminum nitride, and carbon nanotubes (CNTs) of varying sizes and shapes with higher thermal conductivity were selected as composite thermal fillers. Diamond, as a thermal filler, has higher thermal conductivity than conventional fillers, but diamond powder has poor fluidity and cannot form a good thermal conductivity path. The addition of CNTs not only ensures comparable thermal conductivity as a thermal filler, but also provides an optimal thermal conductivity path for the thermally conductive gel due to their one-dimensional pore structure, resulting in even higher thermal conductivity. Furthermore, the addition of aluminum nitride (AN) particles, which are smaller, allows for the distribution of even smaller particles within the CNTs, ensuring efficient and stable filling of the thermally conductive filler. This improves the uniformity of the internal components, eliminates large pores within individual components of the gel, and enhances the gel's thermal conductivity. This approach fully leverages the influence of the properties of the three components on thermal conductivity, significantly improving the gel's thermal conductivity while maintaining the cost and aging resistance of the gel material.

[0026] 2. By combining bisaminosilane coupling agent and diamond in a certain range of ratios, the activated diamond surface is grafted with a certain number of amino groups with high activity that can be cross-linked with the silicone oil matrix. Too much bisaminosilane coupling agent will result in more grafting with epoxy groups, reducing the viscosity and flexible performance of the thermal conductive silicone oil. A small amount of bisaminosilane coupling agent will deteriorate the surface performance of the diamond, affect the interfacial bonding properties with the silicone oil matrix, and affect the stable filling efficiency of the thermal conductive filler. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments.

[0028] raw material

[0029] Some of the raw materials used in the preparation examples and embodiments: bisaminosilane coupling agent model: KH-792; epoxy chain extender model: ADR-4370S; carbon nanotubes (specification 2000-4000 mesh) model: NACODC8; aluminum nitride (specification 1um) model: PT-AlCN; diamond powder purchased from Zhengzhou Smelter Diamond Products; vinyl silicone oil with a viscosity of 1000 mPa·s at room temperature, item number: LG-T1000; hydrogenated silicone oil with a viscosity of 50 mPa·s, model SH-202; the catalyst is a Custer catalyst; the inhibitor is 1-ethynyl-1-cyclohexanol purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.

[0030] The raw materials used in the examples and comparative examples that are not otherwise specified are all conventional products that can be purchased from the market.

[0031] Preparation Example

[0032] Modified diamond preparation example

[0033] Preparation Example 1

[0034] Take 1.5g of diamond powder and add it to 60ml of ethanol solution, ultrasonically grind it for 10 minutes, wash it with 20ml of ethanol and blow it dry, adjust the temperature to 700℃ and low pressure of 105kPa, and deposit it in CO2 atmosphere for 5h to obtain diamond; take bisaminosilane coupling agent in proportion and add it to 50ml of anhydrous ethanol, dilute and mix it evenly with 30ml of distilled water, hydrolyze it in a water bath at 38℃ for 30min, stir and add diamond, the mass ratio of bisaminosilane coupling agent to diamond is 1.2:1; after heating to 60℃ and reacting for 6h, wash it with ethanol and dry it at 60℃ to obtain modified diamond.

[0035] Preparation Example 2

[0036] Take 1.5g of diamond powder and add it to 60ml of ethanol solution, ultrasonically grind it for 10 minutes, wash it with 20ml of ethanol and blow it dry, adjust the temperature to 750℃ and a low pressure of 100kPa, and deposit it in a CO2 atmosphere for 8h to obtain diamond; take bisaminosilane coupling agent in proportion and add it to 50ml of anhydrous ethanol, dilute and mix it evenly with 30ml of distilled water, hydrolyze it in a water bath at 30℃ for 45min, stir and add diamond, the mass ratio of bisaminosilane coupling agent to diamond is 1.2:1; after heating to 70℃ and reacting for 3h, wash it with ethanol and dry it at 60℃ to obtain modified diamond.

[0037] Preparation Example 3

[0038] Take 1.5g of diamond powder and add it to 60ml of ethanol solution, ultrasonically grind it for 10 minutes, wash it with 20ml of ethanol and blow it dry, adjust the temperature to 700℃ and low pressure of 105kPa, and deposit it in CO2 atmosphere for 5h to obtain diamond; take bisaminosilane coupling agent in proportion and add it to 50ml of anhydrous ethanol, dilute and mix it evenly with 30ml of distilled water, hydrolyze it in a water bath at 38℃ for 30min, stir and add diamond, the mass ratio of bisaminosilane coupling agent to diamond is 2.2:1; after heating to 60℃ and reacting for 6h, wash it with ethanol and dry it at 60℃ to obtain modified diamond.

[0039] Preparation Example 4

[0040] Take 1.5g of diamond powder and add it to 60ml of ethanol solution, ultrasonically grind it for 10 minutes, wash it with 20ml of ethanol and blow it dry, adjust the temperature to 700℃ and a low pressure of 105kPa, and deposit it in a CO2 atmosphere for 5h to obtain diamond; take bisaminosilane coupling agent in proportion and add it to 50ml of anhydrous ethanol, dilute and mix it evenly with 30ml of distilled water, hydrolyze it in a water bath at 38℃ for 30min, stir and add diamond, the mass ratio of bisaminosilane coupling agent to diamond is 0.7:1; after heating to 60℃ and reacting for 6h, wash it with ethanol and dry it at 60℃ to obtain modified diamond.

[0041] Preparation Example 5

[0042] 1.5 g of diamond powder was added to 60 ml of ethanol solution, ultrasonically ground for 10 minutes, washed with 20 ml of ethanol and blown dry, and then the temperature was adjusted to 700 ° C and a low pressure of 105 kPa, and deposited in a CO2 atmosphere for 5 hours to obtain diamond; bisaminosilane coupling agent was taken in proportion and added to 50 ml of anhydrous ethanol, diluted and mixed evenly with 30 ml of distilled water, and hydrolyzed in a water bath at 38 ° C for 30 minutes, and diamond was added with stirring. The mass ratio of bisaminosilane coupling agent to diamond was 2.6:1; after heating to 60 ° C for 6 hours, it was washed with ethanol and dried at 60 ° C to obtain modified diamond.

[0043] Preparation example of modified carbon nanotubes

[0044] Preparation Example 6

[0045] Carbon nanotubes were added to a 100 ml mixed solution of sulfuric acid and nitric acid, with a mass ratio of sulfuric acid to nitric acid of 2:3.2, and the temperature was raised to 75° C. for reaction for 10 h to obtain modified carbon nanotubes.

[0046] Preparation Example 7

[0047] Carbon nanotubes were added to 100 ml of a mixed solution of sulfuric acid and nitric acid, with the mass ratio of sulfuric acid to nitric acid being 2:5.1. The temperature was raised to 75° C. and the mixture was reacted for 10 h to obtain modified carbon nanotubes.

[0048] Preparation Example 8

[0049] Carbon nanotubes were added to a 100 ml mixed solution of sulfuric acid and nitric acid, with a mass ratio of sulfuric acid to nitric acid of 1:1, and the temperature was raised to 75° C. for reaction for 10 h to obtain modified carbon nanotubes.

[0050] Example

[0051] Example 1

[0052] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 20 g of hydrogenated silicone oil, 28 g of vinyl silicone oil, 0.6 g of a catalyst, 0.2 g of an inhibitor, 0.1 g of an epoxy chain extender, and 79 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0053] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 16 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 5 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 165°C, the vacuum degree was -0.04MPa, and the speed was 80rpm. After vacuum stirring and mixing for 1 hour, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 40 minutes. The thermal conductive gel was obtained by discharging.

[0054] Example 2

[0055] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0056] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0057] Example 3

[0058] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:8:3.

[0059] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0060] Example 4

[0061] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 3:6:3.

[0062] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0063] Example 5

[0064] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by weight: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:6:5.

[0065] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0066] Example 6

[0067] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 2, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0068] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0069] Example 7

[0070] A highly thermally conductive organosilicon thermally conductive gel comprises the following components in parts by weight: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 3, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0071] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0072] Example 8

[0073] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 4, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0074] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0075] Example 9

[0076] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 5, and modified carbon nanotubes prepared in Preparation Example 6, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0077] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0078] Example 10

[0079] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 7, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0080] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0081] Example 11

[0082] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond and aluminum nitride prepared in Preparation Example 1, and modified carbon nanotubes prepared in Preparation Example 8, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0083] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0084] Comparative Example

[0085] Comparative Example 1

[0086] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises diamond, aluminum nitride, and modified carbon nanotubes obtained in Preparation Example 6, and the mass ratio of diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0087] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0088] Comparative Example 2

[0089] A highly thermally conductive organosilicon thermally conductive gel comprises the following components in parts by weight: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond, aluminum nitride, and carbon nanotubes obtained in Preparation Example 1, wherein the mass ratio of the modified diamond, aluminum nitride, and modified carbon nanotubes is 1:5:1.

[0090] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0091] Comparative Example 3

[0092] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler is the modified diamond prepared in Preparation Example 1, and the mass ratio of the modified diamond to the aluminum nitride is 1:11.

[0093] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0094] Comparative Example 4

[0095] A highly thermally conductive organosilicon thermally conductive gel comprises the following components in parts by weight: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler comprises modified diamond prepared in Preparation Example 1 and modified carbon nanotubes prepared in Preparation Example 6, and the mass ratio of the modified diamond to the modified carbon nanotubes is 1:11.

[0096] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0097] Comparative Example 5

[0098] A highly thermally conductive organic silicone thermally conductive gel comprises the following components in parts by mass: 16 g of hydrogenated silicone oil, 35 g of vinyl silicone oil, 0.3 g of a catalyst, 0.5 g of an inhibitor, 0.3 g of an epoxy chain extender, and 94 g of a composite thermally conductive filler; the composite thermally conductive filler is aluminum nitride and modified carbon nanotubes obtained in Preparation Example 6, and the mass ratio of aluminum nitride to modified carbon nanotubes is 9:3.

[0099] Vinyl silicone oil and epoxy chain extender were mixed in a double planetary mixer at room temperature for 10 minutes, and then the composite thermal conductive filler was added. The composite thermal conductive filler was added in batches, and stirred for 10 minutes after each addition until uniform. The above steps were repeated until all the composite thermal conductive filler was added. The temperature was raised to 140°C, the vacuum degree was 0.09 MPa, and the speed was 50 rpm. After vacuum stirring and mixing for 3 hours, hydrogen-containing silicone oil, inhibitor, and catalyst were added, and mixed at room temperature for 30 minutes. The thermal conductive gel was obtained by discharging.

[0100] Performance testing

[0101] The performance test of the highly thermally conductive silicone thermally conductive gel prepared in Examples 1-11 and Comparative Examples 1-5 was conducted using the following method:

[0102] a. Thermal conductivity test: refer to ISO-CD22007-2 standard test;

[0103] b. Viscosity: Refer to ASTM D4287 standard test;

[0104] c. Hardness: Shore00 test;

[0105] d. Anti-aging properties: Under the conditions of an ambient temperature of 85°C and a humidity of 85%, the test body is subjected to an aging test for 1000 hours. This test mainly examines the limit that the thermal grease can withstand in the harsh environment of high temperature and high humidity. This is called double 85 aging for 1000 hours. The performance is shown in Table 1:

[0106] Table 1 Performance test results

[0107]

[0108] As can be seen from Table 1, compared with Comparative Examples 1-5 and Example 2, the thermal conductivity, viscosity, hardness, and aging resistance of the thermally conductive gel prepared in Example 2 are all superior to those of Comparative Examples 1-5. This indicates that the thermally conductive gel prepared by using modified diamond, aluminum nitride, and modified carbon nanotubes as a composite thermally conductive filler has better efficacy. The modification of the diamond and carbon nanotubes in the composite thermally conductive filler reduces the contact thermal resistance between the internal thermally conductive fillers, improves the thermal conductivity of the overall composite thermally conductive filler, and prevents the hardness of the thermally conductive gel from increasing during high-temperature heat conduction. Diamond, aluminum nitride and carbon nanotubes of different sizes and shapes with higher thermal conductivity are selected as composite thermal conductive fillers. Diamond as a thermal conductive filler has a higher thermal conductivity than conventional fillers. The one-dimensional pore structure of carbon nanotubes can provide a better thermal conductive path for the thermal conductive gel, making the thermal conductive gel have higher thermal conductivity. Aluminum nitride is then added. The aluminum nitride particles are smaller and are filled in the thermal conductive filler. Smaller particles can be distributed in the carbon nanotubes, ensuring the efficiency and stability of the thermal conductive filler filling, improving the uniformity of the internal components, and improving the thermal conductivity of the thermal conductive gel.

[0109] Compared with Examples 2-5, it can be seen that the high thermal conductivity silicone thermal conductive gel prepared in Example 2 has better performance indicators such as thermal conductivity, viscosity, hardness and aging resistance than Examples 4-5. The applicant found that the modified diamond, aluminum nitride and modified carbon nanotubes are mixed in the proportion range disclosed in this application, so that the bonding strength with the silicone oil matrix is ​​better. Too much modified diamond will increase the hardness of the system and affect the flexibility of use of the thermal conductive gel, so that the bonding strength with the silicone oil matrix is ​​better. Too much modified carbon nanotubes will make the thermal conductive gel easily corroded by the outside world, the strength performance is weak, and the aging resistance performance deteriorates.

[0110] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A highly thermally conductive silicone gel, characterized by: The invention is composed of the following components in parts by weight: 16-20 parts of hydrogenated silicone oil, 28-35 parts of vinyl silicone oil, 0.3-0.6 parts of catalyst, 0.2-0.5 parts of inhibitor, 0.1-0.3 parts of epoxy chain extender, and 79-94 parts of composite thermal conductive filler; the composite thermal conductive filler is modified diamond, aluminum nitride, and modified carbon nanotubes in a mass ratio of 1:5:1; The modified diamond preparation method comprises the following steps: adding diamond powder to an ethanol solution, ultrasonically grinding the solution, washing and drying the solution, adjusting the temperature to 700-750° C. and a low pressure of 100-105 kPa, and depositing the solution in a CO2 atmosphere for 5-8 hours to obtain diamond; adding a bisaminosilane coupling agent to anhydrous ethanol, diluting the solution with distilled water and mixing the solution uniformly, hydrolyzing the solution in a water bath at 30-38° C. for 30-45 minutes, adding the diamond solution with stirring, heating the solution to 60-70° C. and reacting the solution for 3-6 hours, and then washing and drying the solution to obtain the modified diamond; The preparation method of the modified carbon nanotubes comprises: adding carbon nanotubes into a mixed solution of sulfuric acid and nitric acid, heating the solution to 70-75° C. for reaction, and obtaining the modified carbon nanotubes.

2. The highly thermally conductive silicone gel according to claim 1, characterized in that: The mass ratio of the bisaminosilane coupling agent to diamond is (1.2-2.2):

1.

3. The high thermal conductivity silicone thermal conductive gel according to claim 1, characterized in that: The mass ratio of the sulfuric acid to the nitric acid is 2:(3.2-5.1).

4. The method for preparing a highly thermally conductive silicone gel according to any one of claims 1 to 3, characterized in that: The following steps are involved: Mix vinyl silicone oil and epoxy chain extender in a double planetary mixer at room temperature for 10-16 minutes, then add the composite thermal conductive filler. Add the composite thermal conductive filler in batches, stir for 5-10 minutes after each addition until uniform, repeat the above steps until all the composite thermal conductive filler is added, raise the temperature to 140-165°C, stir in vacuum, add hydrogen-containing silicone oil, inhibitor, and catalyst, mix at room temperature for 30-40 minutes, and discharge to obtain thermal conductive gel.

5. The method for preparing a highly thermally conductive silicone thermally conductive gel according to claim 4, wherein: The vacuum stirring is performed at a vacuum degree of -0.04-0.09 MPa and a rotation speed of 50-80 rpm for 1-3 hours.

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