High-thermal-conductivity organic silicon gel and preparation method thereof

Abstract

The preparation method comprises the following steps: carrying out lipophilic modification on the surfaces of boron nitride, carbon nanotubes and aluminum nitride by using a silane coupling agent; the preparation method comprises the following steps: adding boron nitride, carbon nanotubes and aluminum nitride subjected to surface treatment into methyl vinyl silicone oil, and fully dispersing by adopting a high-speed shearing machine; mixing the dispersed methyl vinyl silicone oil with polyether modified silicone oil and aminopropyltriethoxysilane, stirring in a vacuum environment by using a planetary stirrer, and gradually adding benzoyl peroxide and vinyl-terminated polydimethylsiloxane in the vacuum stirring process; placing the mixture in a vacuum degassing device, and carrying out multiple degassing operations; and pouring the degassed mixture into a Teflon coating mold, vibrating to remove residual bubbles, and carrying out step-by-step temperature curing in a temperature control oven. The overall heat-conducting property of the material is remarkably improved, and the mechanical strength and the heat-conducting property of a final product are improved.

Description

Technical Field

[0001] The invention relates to the technical field of silicone gel, in particular to a high thermal conductivity organic silicone gel and a preparation method thereof. Background Art

[0002] In recent years, a large amount of fillers have been added to the thermally conductive silicone gel on the market in order to improve the thermal conductivity, which makes the sample viscosity high, the brittleness and stability after curing are poor, resulting in a short service life and unstable performance. Recently, in order to solve this problem, patent No. 200-1616 uses long-chain siloxane coupling to improve the affinity between silicone oil and powder, but the long-chain silane coupling agent is not resistant to high temperature. After curing, it is easy to hydrolyze under high temperature conditions for a long time and react with free vinyl to cause a significant increase in hardness. It is also easy to stick to the device and difficult to peel off. Patent No. JP2001329173A explores the effect of long-chain alkyl siloxanes with different carbon numbers on the hardness and ease of peeling of thermally conductive silicone gel composites after curing on the basis of patent No. 200-1616. It is concluded that the more carbon numbers, the better the affinity of the thermally conductive gel, the lower the hardness, and the greater the difficulty of peeling; when the carbon number is 4, the thermally conductive gel has the best affinity, hardness, and peeling performance. Patent No. 2005-162975 proposes that the use of two or more treatment agents with different molecular weights can improve the filling properties of the powder without damaging the fluidity of the compound.

[0003] At present, the interfacial compatibility between inorganic fillers and silicone matrix is ​​generally poor, resulting in increased interfacial thermal resistance, which limits the overall thermal conductivity of the material. Unstable surface modification effect: The compatibility between fillers and matrix is ​​improved by coupling agents or other surface modification methods, but the effect of these modification treatments may weaken over time or environmental changes, affecting the long-term stability of the material. Multi-step operation increases process complexity: Typical preparation methods for high thermal conductivity silicone gels usually include multiple steps such as filler surface treatment, dispersion, vacuum degassing, and multiple curing. These processes require strict control of parameters, and the slightest carelessness may result in substandard final material performance. During the preparation process, tiny bubbles will remain in the mixture that is not completely degassed, which not only reduces the thermal conductivity of the material, but also weakens the mechanical strength of the material. Thermal aging and environmental stability: High thermal conductivity silicone gels may experience thermal aging in high temperature environments, resulting in decreased thermal conductivity. The long-term durability of materials remains a challenge in harsh environments (such as high humidity and high temperature). Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above and / or existing problems in the existing high thermal conductivity silicone gel and preparation method thereof, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is how to provide a high thermal conductivity silicone gel and a preparation method thereof.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: The embodiment of the present invention provides a high thermal conductivity silicone gel, which includes the following raw materials in parts by weight: 40-60 parts of base silicone oil, 30-40 parts of thermal conductive filler, 5-10 parts of cross-linking agent, 2-5 parts of thickener, 0.5-2 parts of coupling agent, and 0.1-0.5 parts of cross-linking catalyst.

[0008] As a preferred embodiment of the high thermal conductivity silicone gel of the present invention, the base silicone oil is methyl vinyl silicone oil, the thermal conductive filler includes boron nitride, carbon nanotubes and aluminum nitride, the crosslinking agent is vinyl terminated polydimethylsiloxane, the thickener is polyether modified silicone oil, the coupling agent is aminopropyl triethoxysilane, and the crosslinking catalyst is benzoyl peroxide.

[0009] As a preferred scheme of the preparation method of the high thermal conductivity silicone gel described in the present invention, the following steps are performed: a silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride; the surface-treated boron nitride, carbon nanotubes and aluminum nitride are added to methyl vinyl silicone oil and fully dispersed by a high-speed shearing machine; the dispersed methyl vinyl silicone oil is mixed with polyether modified silicone oil and aminopropyl triethoxysilane, and stirred under a vacuum environment by a planetary mixer, and benzoyl peroxide and vinyl-terminated polydimethylsiloxane are gradually added during the vacuum stirring process; the mixture is placed in a vacuum degassing device and degassed for multiple times; the degassed mixture is poured into a Teflon coated mold, and is vibrated to remove residual bubbles, and then cured step by step in a temperature-controlled oven.

[0010] As a preferred embodiment of the method for preparing the high thermal conductivity silicone gel of the present invention, the lipophilic modification of the surfaces of boron nitride, carbon nanotubes and aluminum nitride using a silane coupling agent comprises: the silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.1-0.5% distilled water is added, and the pH value of the solution is adjusted to 4-5 to obtain a 0.5-2% by mass aminopropyltriethoxysilane solution.

[0011] As a preferred embodiment of the method for preparing the high thermal conductivity silicone gel of the present invention, the step of adding the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil and fully dispersing them using a high-speed shearing machine comprises: adding methyl vinyl silicone oil to the stirring tank of the shearing machine so that it occupies 50-70% of the volume of the stirring tank, turning on the shearing machine, setting the initial speed at 500-1000 rpm, gradually adding the boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion, gradually increasing the speed of the shearing machine to 3000-5000 rpm after adding a small amount of filler each time, and maintaining it for 5-10 minutes. After all the fillers are added, gradually increasing the speed of the shearing machine to 8000-12000 rpm and maintaining it for 20-30 minutes.

[0012] As a preferred embodiment of the method for preparing the high thermal conductivity silicone gel of the present invention, the dispersed methyl vinyl silicone oil is mixed with polyether modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum environment using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl terminated polydimethylsiloxane are gradually added, including: after the basic mixing is completed, the pressure in the stirring tank is gradually reduced to -0.09 to -0.1 MPa, vacuum stirring is started, and under vacuum environment, the stirring speed is increased to 500-1000 rpm, and stirred for 20-30 minutes, and at this time, the temperature in the stirring tank is ensured to be controlled at 30-50°C.

[0013] As a preferred embodiment of the method for preparing the high thermal conductive silicone gel of the present invention, the step of placing the mixture in a vacuum degassing device and performing multiple degassing operations includes: pouring the mixture into a degassing container, ensuring that the liquid level does not exceed 2 / 3 of the container capacity, starting the vacuum pump, gradually reducing the pressure to -0.08 to -0.1 MPa, and maintaining it for 10-15 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure, maintain it for 5-10 minutes, so that the residual bubbles have a chance to float to the surface, start the vacuum pump again, repeat the previous degassing steps, maintain the vacuum degree at -0.09 to -0.1 MPa, and maintain it for 10-15 minutes, repeat 2-3 times, and during the last degassing, maintain the vacuum degree at -0.09 to -0.1 MPa, and extend the holding time to 20-30 minutes. After the degassing is completed, the mixture is allowed to stand in a vacuum state for 10-15 minutes.

[0014] As a preferred embodiment of the method for preparing the high thermal conductive silicone gel of the present invention, S5 comprises: setting the vibration frequency of the vibrator at 50-100 Hz and the vibration time at 5-10 min; placing the mold in a temperature-controlled oven, setting the initial temperature at 60-70°C and maintaining it for 2-4 h, then gradually increasing the temperature to 100-120°C and maintaining it for 4-6 h, and finally increasing the temperature to 150-180°C and maintaining it for 2-3 h.

[0015] The beneficial effects of the present invention are as follows: by uniformly dispersing high thermal conductivity fillers such as boron nitride, carbon nanotubes and aluminum nitride in the organosilicon matrix, the organosilicon gel of the present invention significantly improves the overall thermal conductivity of the material. The lipophilicity of the filler surface is modified by a silane coupling agent, which enhances the interface compatibility between the filler and the organosilicon matrix, reduces the interface thermal resistance, and ensures the uniformity and long-term stability of the material. The present invention uses optimized high-speed shear dispersion and planetary stirring technology, stirs and degasses multiple times in a vacuum environment, ensures the uniform distribution of the material during processing, reduces residual bubbles, and improves the mechanical strength and thermal conductivity of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 The present invention is a process flow chart of the preparation method of high thermal conductive silicone gel. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0018] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0020] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Example 1

[0021] Reference Figure 1 , which is an embodiment of the present invention.

[0022] A method for preparing high thermal conductive silicone gel: Prepare 80 parts of methyl vinyl silicone oil, 40 parts of boron nitride, carbon nanotubes and aluminum nitride, 5 parts of vinyl-terminated polydimethylsiloxane, 2 parts of polyether-modified silicone oil, 0.5 parts of aminopropyl triethoxysilane, and 0.1 parts of benzoyl peroxide for later use; The silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride. The silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.1% distilled water is added, and the pH value of the solution is adjusted to 4 to obtain a 0.5% by mass aminopropyltriethoxysilane solution; Add the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil, use a high-speed shearing machine to fully disperse, add methyl vinyl silicone oil to the stirring tank of the shearing machine so that it occupies 50% of the volume of the stirring tank, turn on the shearing machine, set the initial speed at 500rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion. After adding a small amount of filler each time, gradually increase the speed of the shearing machine to 3000rpm and keep it for 5min. After all the fillers are added, gradually increase the speed of the shearing machine to 8000rpm and keep it for 20min. The dispersed methyl vinyl silicone oil was mixed with polyether-modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl-terminated polydimethylsiloxane were gradually added. After the basic mixing was completed, the pressure in the stirring tank was gradually reduced to -0.09 MPa, and vacuum stirring was started. Under vacuum, the stirring speed was increased to 500 rpm and stirred for 20 minutes. At this time, the temperature in the stirring tank was ensured to be controlled at 30°C. Pour the mixture into the degassing container, make sure the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.08MPa, and maintain for 10 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 5 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. Keep the vacuum degree at -0.09MPa and maintain for 10 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.09MPa and extend the holding time to 20 minutes. Degassing is complete. The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles. Then, it is cured step by step in a temperature-controlled oven with the vibration frequency of the vibrator set at 50 Hz and the vibration time at 5 min. The mold is placed in a temperature-controlled oven with the initial temperature set to 60 °C for 2 h, then the temperature is gradually increased to 100 °C and maintained for 4 h, and finally the temperature is increased to 150 °C and maintained for 2 h. Example 2

[0023] A method for preparing high thermal conductive silicone gel: Prepare 85 parts of methyl vinyl silicone oil, 45 parts of boron nitride, carbon nanotubes and aluminum nitride, 6 parts of vinyl-terminated polydimethylsiloxane, 3 parts of polyether-modified silicone oil, 1 part of aminopropyl triethoxysilane, and 0.2 parts of benzoyl peroxide for use; The silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride. The silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.2% distilled water is added, and the pH value of the solution is adjusted to 4.2 to obtain a 0.8% by mass aminopropyltriethoxysilane solution; Add the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil, use a high-speed shear to fully disperse, add methyl vinyl silicone oil to the stirring tank of the shear to make it account for 55% of the volume of the stirring tank, turn on the shear, set the initial speed at 600rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion. After adding a small amount of filler each time, gradually increase the shear speed to 3500rpm and keep it for 6min. After all the fillers are added, gradually increase the shear speed to 9000rpm and keep it for 22min. The dispersed methyl vinyl silicone oil was mixed with polyether-modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl-terminated polydimethylsiloxane were gradually added. After the basic mixing was completed, the pressure in the stirring tank was gradually reduced to -0.092MPa, and vacuum stirring was started. Under vacuum, the stirring speed was increased to 600rpm and stirred for 22min. At this time, the temperature in the stirring tank was ensured to be controlled at 35°C. Pour the mixture into the degassing container, make sure the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.085MPa, and maintain for 11 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 6 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. The vacuum degree is maintained at -0.092MPa and maintained for 11 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.092MPa and extend the holding time to 22 minutes. Degassing is complete; The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles. Then, it is cured step by step in a temperature-controlled oven with the vibration frequency of the vibrator set at 60 Hz and the vibration time at 6 min. The mold is placed in a temperature-controlled oven with the initial temperature set at 62 °C for 2.5 h, then the temperature is gradually increased to 105 °C and maintained for 4.5 h, and finally the temperature is increased to 160 °C and maintained for 2.2 h. Example 3

[0024] A method for preparing high thermal conductive silicone gel: Prepare 90 parts of methyl vinyl silicone oil, 50 parts of boron nitride, carbon nanotubes and aluminum nitride, 7 parts of vinyl-terminated polydimethylsiloxane, 4 parts of polyether-modified silicone oil, 1.5 parts of aminopropyl triethoxysilane, and 0.3 parts of benzoyl peroxide for later use; The silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride. The silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.3% distilled water is added, and the pH value of the solution is adjusted to 4.4 to obtain a 1.2% by mass aminopropyltriethoxysilane solution; Add the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil, use a high-speed shear to fully disperse, add methyl vinyl silicone oil to the stirring tank of the shear to make it account for 60% of the volume of the stirring tank, turn on the shear, set the initial speed at 700rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion. After adding a small amount of filler each time, gradually increase the shear speed to 4000rpm and keep it for 7min. After all the fillers are added, gradually increase the shear speed to 10000rpm and keep it for 25min. The dispersed methyl vinyl silicone oil was mixed with polyether-modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl-terminated polydimethylsiloxane were gradually added. After the basic mixing was completed, the pressure in the stirring tank was gradually reduced to -0.095 MPa, and vacuum stirring was started. Under vacuum, the stirring speed was increased to 700 rpm and stirred for 25 minutes. At this time, the temperature in the stirring tank was ensured to be controlled at 40°C. Pour the mixture into the degassing container, make sure the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.09MPa, and maintain for 13 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 7 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. Keep the vacuum degree at -0.095MPa and maintain for 13 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.095MPa and extend the holding time to 25 minutes. Degassing is complete. The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles. Then, it is cured step by step in a temperature-controlled oven with the vibration frequency of the vibrator set at 70 Hz and the vibration time set at 7 minutes. The mold is placed in a temperature-controlled oven with the initial temperature set to 65°C for 3 hours, then the temperature is gradually increased to 110°C and maintained for 5 hours, and finally the temperature is increased to 170°C and maintained for 2.5 hours. Example 4

[0025] Prepare 95 parts of methyl vinyl silicone oil, 70 parts of boron nitride, carbon nanotubes and aluminum nitride, 9 parts of vinyl-terminated polydimethylsiloxane, 4.5 parts of polyether-modified silicone oil, 1.8 parts of aminopropyl triethoxysilane, and 0.4 parts of benzoyl peroxide for use; The silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride. The silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.4% distilled water is added, and the pH value of the solution is adjusted to 4.8 to obtain a 1.8% by mass aminopropyltriethoxysilane solution; Add the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil, use a high-speed shearing machine to fully disperse, add methyl vinyl silicone oil to the stirring tank of the shearing machine so that it accounts for 65% of the volume of the stirring tank, turn on the shearing machine, set the initial speed at 900 rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion. After adding a small amount of filler each time, gradually increase the speed of the shearing machine to 4500 rpm and keep it for 9 minutes. After all the fillers are added, gradually increase the speed of the shearing machine to 11000 rpm and keep it for 28 minutes; The dispersed methyl vinyl silicone oil was mixed with polyether-modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl-terminated polydimethylsiloxane were gradually added. After the basic mixing was completed, the pressure in the stirring tank was gradually reduced to -0.098 MPa, and vacuum stirring was started. Under vacuum, the stirring speed was increased to 900 rpm and stirred for 28 minutes. At this time, the temperature in the stirring tank was ensured to be controlled at 45°C. Pour the mixture into the degassing container, make sure the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.095MPa, and maintain for 14 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 9 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. The vacuum degree is maintained at -0.098MPa and maintained for 14 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.098MPa and extend the holding time to 28 minutes. Degassing is complete; The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles. Then, it is cured step by step in a temperature-controlled oven with the vibration frequency of the vibrator set at 90 Hz and the vibration time at 9 minutes. The mold is placed in a temperature-controlled oven with the initial temperature set to 68°C for 3.5 hours, then the temperature is gradually increased to 115°C and maintained for 5.5 hours, and finally the temperature is increased to 175°C and maintained for 2.8 hours. Example 5

[0026] Prepare 100 parts of methyl vinyl silicone oil, 75 parts of boron nitride, carbon nanotubes and aluminum nitride, 10 parts of vinyl-terminated polydimethylsiloxane, 5 parts of polyether-modified silicone oil, 2 parts of aminopropyl triethoxysilane, and 0.5 parts of benzoyl peroxide for use; The silane coupling agent is used to modify the lipophilicity of the surfaces of boron nitride, carbon nanotubes and aluminum nitride. The silane coupling agent solution is prepared as follows: anhydrous ethanol is selected as a solvent, 0.5% distilled water is added, and the pH value of the solution is adjusted to 5 to obtain a 2% by mass aminopropyltriethoxysilane solution; Add the surface-treated boron nitride, carbon nanotubes and aluminum nitride to methyl vinyl silicone oil, use a high-speed shear to fully disperse, add methyl vinyl silicone oil to the stirring tank of the shear to make it account for 70% of the volume of the stirring tank, turn on the shear, set the initial speed at 1000rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride to the stirring tank in proportion. After adding a small amount of filler each time, gradually increase the shear speed to 5000rpm and keep it for 10min. After all the fillers are added, gradually increase the shear speed to 12000rpm and keep it for 30min. The dispersed methyl vinyl silicone oil was mixed with polyether-modified silicone oil and aminopropyl triethoxysilane, and stirred under vacuum using a planetary mixer. During the vacuum stirring process, benzoyl peroxide and vinyl-terminated polydimethylsiloxane were gradually added. After the basic mixing was completed, the pressure in the stirring tank was gradually reduced to -0.1MPa, and vacuum stirring was started. In the vacuum environment, the stirring speed was increased to 1000rpm and stirred for 30 minutes. At this time, the temperature in the stirring tank was controlled at 50°C. Pour the mixture into the degassing container, make sure the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.1MPa, and maintain for 15 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 10 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. Keep the vacuum degree at -0.1MPa and maintain for 15 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.1MPa and extend the holding time to 30 minutes. Degassing is complete. The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles. Then, it is cured step by step in a temperature-controlled oven with the vibration frequency of the vibrator set at 100 Hz and the vibration time set at 10 minutes. The mold is placed in a temperature-controlled oven with the initial temperature set to 70°C for 4 hours, then the temperature is gradually increased to 120°C and maintained for 6 hours, and finally the temperature is increased to 180°C and maintained for 3 hours.

[0027] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A high thermal conductivity silicone gel, characterized in that: The invention is prepared from the following raw materials in parts by weight: 80-100 parts of basic silicone oil, 40-75 parts of thermal conductive filler, 5-10 parts of crosslinking agent, 2-5 parts of thickener, 0.5-2 parts of coupling agent and 0.1-0.5 parts of crosslinking catalyst.

2. The high thermal conductivity silicone gel according to claim 1, characterized in that: The base silicone oil is methyl vinyl silicone oil, the thermal conductive filler includes boron nitride, carbon nanotubes and aluminum nitride, the crosslinking agent is vinyl-terminated polydimethylsiloxane, the thickener is polyether-modified silicone oil, the coupling agent is aminopropyl triethoxysilane, and the crosslinking catalyst is dibenzoyl peroxide.

3. A method for preparing a high thermal conductive silicone gel, characterized in that: include: S1: Use silane coupling agent to modify the lipophilicity of boron nitride, carbon nanotubes and aluminum nitride surfaces; S2: adding the surface treated boron nitride, carbon nanotubes and aluminum nitride into methyl vinyl silicone oil and fully dispersing them using a high-speed shearing machine; S3: Mix the dispersed methyl vinyl silicone oil with polyether modified silicone oil and aminopropyl triethoxysilane, and stir them under vacuum using a planetary mixer. During the vacuum stirring process, gradually add benzoyl peroxide and vinyl terminated polydimethylsiloxane; S4: placing the mixture in a vacuum degassing device and performing multiple degassing operations; S5: The degassed mixture is poured into a Teflon-coated mold and vibrated to remove residual bubbles, and then cured in a temperature-controlled oven in stages.

4. The method for preparing a highly thermally conductive silicone gel according to claim 3, characterized in that: The S1 includes: The silane coupling agent solution is prepared as follows: Anhydrous ethanol is selected as a solvent, 0.1-0.5% distilled water is added, and the pH value of the solution is adjusted to 4-5 to obtain a 0.5-2% by mass aminopropyltriethoxysilane solution.

5. The method for preparing a 0.5-2% by mass aminopropyltriethoxysilane solution of a high thermal conductive silicone gel according to claim 3, characterized in that: The S2 includes: Add methyl vinyl silicone oil to the mixing tank of the shearing machine so that it occupies 50-70% of the volume of the mixing tank. Turn on the shearing machine, set the initial speed at 500-1000rpm, and gradually add boron nitride, carbon nanotubes and aluminum nitride into the mixing tank in proportion. After adding a small amount of filler each time, gradually increase the shearing machine speed to 3000-5000rpm and keep it for 5-10min. After all the fillers are added, gradually increase the shearing machine speed to 8000-12000rpm and keep it for 20-30min.

6. The method for preparing a highly thermally conductive silicone gel according to claim 3, characterized in that: The S3 includes: After the basic mixing is completed, gradually reduce the pressure in the stirring tank to -0.09 to -0.1MPa, start vacuum stirring, and increase the stirring speed to 500-1000rpm under vacuum environment. Stir for 20-30 minutes. At this time, ensure that the temperature in the stirring tank is controlled at 30-50℃.

7. The method for preparing a highly thermally conductive silicone gel according to claim 3, characterized in that: The S4 includes: Pour the mixture into the degassing container, making sure that the liquid level does not exceed 2 / 3 of the container capacity, start the vacuum pump, gradually reduce the pressure to -0.08 to -0.1 MPa, and maintain for 10-15 minutes. After the initial degassing, slowly restore the pressure in the container to normal pressure and maintain for 5-10 minutes to allow the residual bubbles to float to the surface. Start the vacuum pump again and repeat the previous degassing steps. The vacuum degree is maintained at -0.09 to -0.1 MPa and maintained for 10-15 minutes. Repeat 2-3 times. During the last degassing, maintain the vacuum degree at -0.09 to -0.1 MPa and extend the holding time to 20-30 minutes. After degassing, let the mixture stand under vacuum for 10-15 minutes.

8. The method for preparing a highly thermally conductive silicone gel according to claim 3, characterized in that: The S5 includes: The vibration frequency of the vibrator is set at 50-100Hz, and the vibration time is 5-10min; the mold is placed in a temperature-controlled oven, the initial temperature is set to 60-70℃, maintained for 2-4h, then the temperature is gradually increased to 100-120℃, and maintained for 4-6h, and finally the temperature is increased to 150-180℃, and maintained for 2-3h.

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