A preparation method of 8W insulating thermal conductive silicone grease

Abstract

The present invention relates to the technical field of thermal grease preparation, and more particularly to a method for preparing 8W insulating thermal grease. 2-phenyl-6-ethyl trimethoxysilyl-hexamethylcyclotetrasiloxane is used as a filling base material and is mixed with a thermally conductive filler by high-temperature kneading for 30 minutes, and the hydroxyl group on the surface of the thermally conductive filler in the mixed oil-powder mixture is hydrolyzed with the trimethoxy group in 2-phenyl-6-ethyl trimethoxysilyl-hexamethylcyclotetrasiloxane to generate methanol, and volatilizes and removes at high temperature, and phenylsiloxane directly wraps the surface of the thermally conductive powder, increases the filling amount of nano zinc oxide and aluminum nitride thermally conductive filler, thereby improving thermal conductivity and reducing thermal resistance. The present invention uses 2-phenyl-6-ethyl trimethoxysilyl-hexamethylcyclotetrasiloxane as a filling base material, and uses aluminum nitride, nano zinc oxide and single crystal aluminum oxide as thermally conductive fillers, thereby achieving higher thermal conductivity and better insulation performance.

Description

Technical Field

[0001] The invention relates to the technical field of thermal conductive silicone grease preparation, and in particular to a method for preparing 8W insulating thermal conductive silicone grease. Background Art

[0002] Thermal grease is an interface thermal conductive material with good thermal conductivity. It has extremely low thermal resistance and use thickness, and can be compressed to 0.1mm or even lower. In order to increase thermal conductivity and reduce thermal resistance, most of the thermal conductive fillers of high thermal conductive grease on the market are filled with metal aluminum powder, which makes the conductivity of thermal conductive grease unable to meet the insulation requirements of the terminal for thermal conductive grease, and the maximum thermal conductivity is only 6W / mK, which cannot break through higher thermal conductivity.

[0003] Specifically, the following defects exist: (1) The thermal conductivity cannot exceed 6W / mK: The highest thermal conductivity of high thermal conductivity silicone grease on the market is only 6W / mK, which is difficult to meet the demand for higher thermal conductivity performance; (2) The product is conductive but not insulating: Since metal aluminum powder is used as a thermal conductive filler, the thermal conductive silicone grease is conductive and cannot meet the terminal's insulation requirements for thermal conductive silicone grease; (3) Aluminum powder is easily oxidized during long-term use: Metal aluminum powder is easily oxidized during long-term use, resulting in a decrease in the overall performance of the thermal conductive silicone grease, affecting the reliability and life of the equipment. Summary of the invention

[0004] The present invention proposes a preparation method of 8W insulating thermally conductive silicone grease, which achieves higher thermal conductivity and better insulation performance by using 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane as a filling substrate and using aluminum nitride, nano zinc oxide and single crystal aluminum oxide as thermally conductive fillers.

[0005] The technical scheme adopted by the present invention is: a preparation method of 8W insulating thermal conductive silicone grease, wherein 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane is used as a filling base material and mixed with a thermal conductive filler through high-temperature kneading for 30 minutes, hydroxyl groups on the surface of the thermal conductive filler in the mixed oil-powder mixture and trimethoxy groups in 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane are hydrolyzed to generate methanol, which is volatilized and removed at high temperature, and phenylsiloxane directly wraps the surface of the thermal conductive powder, thereby increasing the filling amount of nano zinc oxide and aluminum nitride thermal conductive fillers, thereby improving the thermal conductivity and reducing thermal resistance.

[0006] As a further improvement of the present invention, the filling substrate includes nano zinc oxide, aluminum nitride and single crystal aluminum oxide.

[0007] As a further improvement of the present invention, the 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane, nano zinc oxide, aluminum nitride and single crystal aluminum oxide are counted in parts by weight: 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane accounts for 80-120 parts, nano zinc oxide accounts for 700-850 parts, and aluminum oxide accounts for 10-30 parts.

[0008] As a further improvement of the present invention, the viscosity of the 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane is 50 cps.

[0009] As a further improvement of the present invention, the particle size of the nano zinc oxide is less than 1 um; the particle size of the nitrogen oxide is 8-12 um; and the particle size of the aluminum oxide is 4-6 um.

[0010] Beneficial effects of the present invention: (1) Thermal conductivity reaches 8 W / mK: The present invention uses 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane as a filling base material and optimizes the ratio of the thermally conductive filler to successfully increase the thermal conductivity of the thermally conductive silicone grease to above 8 W / mK; the trimethoxy group in 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane can react with the hydroxyl group on the surface of the thermally conductive filler to remove the hydroxyl group, so that the high molecular organic matter can better wrap the surface of the thermally conductive powder, thereby increasing the filling amount of the thermally conductive filler.

[0011] (2) The product is insulated and non-conductive, with a breakdown voltage ≥6KV / mm: The present invention does not use metal fillers, but uses insulating materials such as aluminum nitride, nano zinc oxide and single crystal aluminum oxide as thermal conductive fillers; it has good insulation properties, ensuring that the thermal grease is non-conductive during use and meets the terminal's requirements for insulation performance.

[0012] (3) Good aging reliability: After the present invention passes the reliability test, the thermal conductivity of the product does not change by more than 10%; since phenylsiloxane contains phenyl groups, the entire molecular structure has better high temperature resistance, thereby improving the reliability of long-term use of thermal grease; through the high-temperature kneading process, it is ensured that the hydroxyl groups on the surface of the thermal conductive filler are completely reacted, thereby avoiding performance degradation during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural diagram of 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane of a method for preparing 8W insulating thermally conductive silicone grease of the present invention;

[0014] Figure 2 It is a reaction principle diagram of a method for preparing 8W insulating thermal conductive silicone grease of the present invention. DETAILED DESCRIPTION

[0015] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0016] The invention provides a preparation method of 8W insulating thermally conductive silicone grease. The grease comprises the following steps: kneading 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane as a filling base material with a thermally conductive filler for 30 minutes at high temperature, wherein hydroxyl groups on the surface of the thermally conductive filler in the mixed oil-powder mixture and trimethoxy groups in the 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane are hydrolyzed to generate methanol, which is volatilized and removed at high temperature, and phenylsiloxane directly wraps the surface of the thermally conductive powder, thereby increasing the filling amount of nano zinc oxide and aluminum nitride thermally conductive fillers, thereby increasing the thermal conductivity and reducing the thermal resistance.

[0017] The filling substrate of the present invention includes nano zinc oxide, aluminum nitride and single crystal aluminum oxide. The weight proportions of 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane, nano zinc oxide, aluminum nitride and single crystal aluminum oxide are as follows: 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane accounts for 80-120 parts, nano zinc oxide accounts for 700-850 parts, and aluminum oxide accounts for 10-30 parts. The viscosity of 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane is 50cps. The particle size of nano zinc oxide is less than 1um; the particle size of nitrogen oxide is 8-12um; and the particle size of aluminum oxide is 4-6um.

[0018] The preparation test was carried out according to the above method, and the test cases included Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2, as shown in the following table. (Phenylsiloxane is the abbreviation of 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane)

[0019]

[0020] The performance of the finished thermal greases obtained in Example 1, Example 2, Example 3 and Comparative Example 1 and Comparative Example 2 was tested, and the specific performance data are shown in the following table.

[0021]

[0022] It can be seen from the above table that (1) the overall effect of Example 1 meets the product performance, and its comprehensive performance is better than that of other examples and comparative examples;

[0023] (2) Example 2 is compared with Example 1, but the amount of aluminum nitride is reduced and the amount of aluminum oxide is increased. Due to the reduction of aluminum nitride, the overall thermal conductivity is reduced; however, aluminum oxide is easier to fill than aluminum nitride, and the viscosity is slightly reduced. The reliability performance does not change much before and after.

[0024] (3) Compared with Example 1, Example 3 greatly increases the filling ratio of aluminum oxide, which greatly reduces the thermal conductivity. Compared with Example 2, due to the imbalance of aluminum oxide ratio, the small particle size accounts for too much, resulting in increased viscosity. The reliability performance does not change much before and after.

[0025] (4) Comparative Example 1 Compared with Example 1, methyl silicone oil is used in combination with a silane treatment agent to replace phenyl siloxane. The hydroxyl group on the surface of the powder is not effectively removed, resulting in a significant increase in the viscosity of the thermal grease. The increase in viscosity also leads to an increase in thermal resistance. Since the organic part does not contain phenyl, the high temperature resistance is poor, causing the entire product to harden after the reliability test.

[0026] (5) Comparative Example 2 Compared with Comparative Example 1, the amount of silane treatment agent used was increased, which could reduce the viscosity of the thermal grease. However, the effect of Example 1 was still not achieved, and the grease became hard after the reliability test.

[0027] In summary, the thermal conductive silicone grease product prepared by the preparation method of an 8W insulating thermal conductive silicone grease of the present invention can achieve a thermal conductivity of more than 8W / mK, extremely low thermal resistance, good viscosity and insulation strength. At the same time, the present invention ensures that the hydroxyl groups on the surface of the thermal conductive filler are completely reacted through a high-temperature kneading process, thereby improving the long-term use reliability of the product. It has broad application prospects, especially in the automotive electronics, new energy, energy storage, LED, PC, power supply and other industries, and can significantly improve the thermal conductivity and reliability of the equipment.

[0028] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing 8W insulating thermally conductive silicone grease, characterized in that: 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane is used as a filling base material and mixed with a thermal conductive filler by high-temperature kneading for 30 minutes. The hydroxyl group on the surface of the thermal conductive filler in the mixed oil-powder mixture and the trimethoxy group in 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane are hydrolyzed to generate methanol, which is volatilized and removed at high temperature. Phenyl siloxane directly wraps the surface of the thermal conductive powder, increases the filling amount of nano zinc oxide and aluminum nitride thermal conductive fillers, thereby improving the thermal conductivity and reducing thermal resistance.

2. The method for preparing an 8W insulating thermally conductive silicone grease according to claim 1, characterized in that: The filling substrate includes nano zinc oxide, aluminum nitride and single crystal aluminum oxide.

3. The method for preparing 8W insulating thermally conductive silicone grease according to claim 2, characterized in that: The 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane, nano zinc oxide, aluminum nitride and single crystal aluminum oxide are counted in parts by weight: 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane accounts for 80-120 parts, nano zinc oxide accounts for 700-850 parts, and aluminum oxide accounts for 10-30 parts.

4. The method for preparing 8W insulating thermally conductive silicone grease according to claim 3, characterized in that: The viscosity of the 2-phenyl-6-ethyltrimethoxysilyl-hexamethylcyclotetrasiloxane is 50 cps.

5. The method for preparing 8W insulating thermally conductive silicone grease according to claim 3, characterized in that: The particle size of the nano zinc oxide is less than 1 um; the particle size of the nitrogen oxide is 8-12 um; and the particle size of the aluminum oxide is 4-6 um.

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