Thermally conductive silicone grease, and preparation method and application thereof

Abstract

The application provides a heat-conducting silicone grease and a preparation method and application thereof, and the preparation raw materials of the heat-conducting silicone grease comprise the following components in parts by weight: 12-20 parts of silicone oil; 2-5 parts of silane coupling agent; 0.2-0.5 parts of powder treatment agent; and 150-200 parts of heat-conducting powder. The silane coupling agent comprises a single-terminal alkoxy type silane coupling agent; and the heat-conducting powder comprises a combination of zinc oxide, aluminum oxide and aluminum powder. The preparation raw materials of the heat-conducting silicone grease provided by the application comprise a combination of silicone oil, silane coupling agent, powder treatment agent and heat-conducting powder, and through the screening and synergistic compounding of specific components, especially the introduction of specific silane coupling agent, powder treatment agent and specific heat-conducting powder, the prepared heat-conducting silicone grease has ultralow thermal resistance and yield stress matched with the thermal resistance, so that the heat-conducting silicone grease has good heat dissipation capacity and operability.

Description

Technical Field

[0001] This invention belongs to the field of silicone grease technology, and relates to a thermally conductive silicone grease, its preparation method and application, specifically to an ultra-low thermal resistance yield stress type thermally conductive silicone grease, its preparation method and application. Background Technology

[0002] Effective heat dissipation for electronic devices operating under high power density conditions is essential for their stable and long-term use. Thermal grease, as a common thermal interface material, has wide applications in electronic device heat dissipation. Applying thermal grease between electronic and cooling components not only fills the gap between them but also acts as a heat transfer medium, promoting heat transfer. Interfacial thermal resistance is an important indicator of the heat dissipation capability of thermal grease; the lower the interfacial thermal resistance, the better the heat dissipation performance. Currently, most thermal greases have an interfacial thermal resistance between 0.05 K·cm. 2 / W to 0.1K·cm 2 Between / W. Therefore, it is necessary to develop thermal greases with ultra-low interfacial thermal resistance to meet the ever-increasing heat dissipation requirements of electronic devices.

[0003] Thermal greases exhibiting yield stress behavior only flow under external forces exceeding their yield stress. This yield stress behavior prevents sagging and post-dispensing expansion, facilitating both manual application and automated dispensing. Yield stress is a key parameter for evaluating the yield stress behavior of thermal greases. However, the interfacial thermal resistance of thermal greases does not perfectly match their yield stress, requiring a trade-off between the two.

[0004] Therefore, it is desirable in the art to develop a thermal grease that has both low interfacial thermal resistance and an interfacial thermal resistance that matches the yield stress. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a thermally conductive silicone grease, its preparation method and application.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a thermal grease, wherein the raw materials for preparing the thermal grease, by weight, comprise the following components:

[0008]

[0009] The silane coupling agent includes a single-terminal alkoxy-type silane coupling agent;

[0010] The thermally conductive powder comprises a combination of zinc oxide, aluminum oxide, and aluminum powder.

[0011] The thermal grease provided by this invention comprises a combination of organosilicon oil, silane coupling agent, powder treatment agent, and thermally conductive powder. Through the screening and synergistic compounding of specific components, especially the introduction of a single-terminal alkoxy-type silane coupling agent, powder treatment agent, and specific thermally conductive powder, the prepared thermal grease exhibits ultra-low thermal resistance and a yield stress matching the thermal resistance, resulting in good heat dissipation capacity and operability. The introduction of the single-terminal alkoxy-type silane coupling agent improves the compatibility between the thermally conductive powder and organosilicon oil, achieving highly uniform dispersion of the thermally conductive powder. Furthermore, it enhances the interfacial interaction between the thermally conductive powder and organosilicon oil, reducing lattice vibration mismatch and thus lowering the thermal resistance of the thermal grease. The introduction of the powder treatment agent further improves the uniform dispersion of the powder treatment agent and the thermally conductive powder in the organosilicon oil.

[0012] In this invention, the raw materials for preparing the thermal grease, by weight, may include 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, etc. of organosilicon oil.

[0013] In this invention, the raw materials for preparing the thermal grease, by weight, include 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc., of silane coupling agent.

[0014] In this invention, the raw materials for preparing the thermal grease, by weight, include powder treatment agents in amounts of 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc.

[0015] In this invention, the raw materials for preparing the thermal grease, by weight, include thermally conductive powder in amounts of 150 parts, 155 parts, 160 parts, 165 parts, 170 parts, 175 parts, 180 parts, 185 parts, 190 parts, 195 parts, 200 parts, etc.

[0016] Preferably, the single-terminal alkoxy silane coupling agent has the structure shown in formula (I):

[0017]

[0018] Where m is an integer between 30 and 40, such as 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40.

[0019] It should be noted that n-Bu is derived from n-butyllithium (n-BuLi), the raw material used to synthesize this silane coupling agent, and has no special significance.

[0020] The single-terminal alkoxy-type silane coupling agent of the present invention has three hydrolyzable alkoxy groups at one end and a n-butyl-terminated siloxane chain at the other end. The alkoxy groups in this silane coupling agent can rapidly hydrolyze to form silanol groups during use. These silanol groups can undergo dehydration condensation reactions with the hydroxyl groups on the surface of thermally conductive powders such as zinc oxide, alumina, and aluminum powder, thereby forming stable ether bonds. The three hydrolyzable alkoxy groups enable this silane coupling agent to undergo rapid hydrolysis and form effective and stable bonds with the thermally conductive powders. Furthermore, the siloxane chain has a strong affinity for silicone oils, which can enhance the interfacial interaction between the thermally conductive powders and silicone oils.

[0021] For example, the single-terminal alkoxy silane coupling agent can be FM-0815J.

[0022] Preferably, the silicone oil is selected from any one or a combination of at least two of dimethyl silicone oil, phenyl silicone oil, vinyl silicone oil, amino silicone oil, and methylphenyl silicone oil, with dimethyl silicone oil and / or phenyl silicone oil being more preferred.

[0023] Preferably, the viscosity of the silicone oil at 25°C is 50–500 mm. 2 / s, for example, 50mm 2 / s, 100mm 2 / s, 150mm 2 / s, 200mm 2 / s, 250mm 2 / s, 300mm 2 / s, 350mm 2 / s, 400mm 2 / s, 450mm 2 / s, 500mm 2 / s etc.

[0024] Preferably, the powder treatment agent comprises dodecyltrimethoxysilane, which has the structure of formula (II) shown below:

[0025]

[0026] During use, the three hydrolyzable alkoxy groups at the end of the dodecyltrimethoxysilane can be rapidly hydrolyzed and react with the hydroxyl groups on the surface of the thermally conductive powders zinc oxide, alumina, and aluminum powder to form stable ether bonds. By introducing dodecyltrimethoxysilane, it is possible to further achieve uniform dispersion of aluminum powder, alumina, and zinc oxide in silicone oil.

[0027] Preferably, the zinc oxide comprises spherical zinc oxide with an average particle size of less than 1 μm (e.g., 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm, etc.).

[0028] Preferably, the alumina comprises spherical alumina with an average particle size of 0.3 to 2 μm (e.g., 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, etc.).

[0029] Preferably, the aluminum powder comprises spherical aluminum powder with an average particle size of 1 to 10 μm (e.g., 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, etc.), and more preferably spherical aluminum powder with an average particle size of 1 to 8 μm.

[0030] Preferably, the aluminum powder comprises a combination of spherical aluminum powder with an average particle size of 1-3 μm (e.g., 1 μm, 1.3 μm, 1.5 μm, 1.8 μm, 2 μm, 2.3 μm, 2.5 μm, 2.8 μm, 3 μm, etc.) and spherical aluminum powder with an average particle size of 4-6 μm (e.g., 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5 μm, 5.2 μm, 5.4 μm, 5.6 μm, 5.8 μm, 6 μm, etc.).

[0031] Preferably, the thermally conductive powder comprises: 15-23 parts (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, etc.) of spherical zinc oxide with an average particle size of less than 1 μm, and 25-35 parts (e.g., 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, etc.) of spherical zinc oxide with an average particle size of less than 1 μm. Spherical alumina with a diameter of 0.3–2 μm, 30–36 parts (e.g., 30, 31, 32, 33, 34, 35, 36, etc.) of spherical aluminum powder with an average particle size of 1–3 μm, and 97–100 parts (e.g., 97, 97.5, 98, 98.5, 99, 99.5, 100, etc.) of spherical aluminum powder with an average particle size of 4–6 μm.

[0032] Preferably, the interfacial thermal resistance of the thermal grease is ≤0.04 K·cm. 2 / W, for example 0.04K·cm 2 / W, 0.035K·cm 2 / W, 0.033K·cm 2 / W, 0.03K·cm 2 / W, 0.025K·cm 2 / W, 0.022K·cm2 / W, 0.019K·cm 2 / W etc.

[0033] In a second aspect, the present invention provides a method for preparing thermal grease as described in the first aspect, the method comprising the following steps:

[0034] The formulated amounts of organosilicon oil, silane coupling agent, powder treatment agent, and thermally conductive powder are mixed to obtain the thermally conductive silicone grease.

[0035] As a preferred embodiment of the present invention, the preparation method includes the following steps:

[0036] The formulated amounts of silicone oil and powder treatment agent are mixed for the first time, then thermally conductive powder and silane coupling agent are added, and the mixture is mixed for the second time. The mixture is then heated and mixed for the third time to obtain the thermally conductive silicone grease.

[0037] As a further preferred embodiment of the present invention, the preparation method includes the following steps:

[0038] The formulated amounts of silicone oil and powder treatment agent are first mixed, then a mixture of thermally conductive powder and silane coupling agent is added, followed by a second mixing, heating, and a third mixing to obtain the thermally conductive silicone grease. Pre-mixing the thermally conductive powder and silane coupling agent before mixing with other raw materials is more conducive to achieving uniform dispersion of the thermally conductive powder.

[0039] Preferably, the thermally conductive powder is dried before being added.

[0040] Preferably, the drying temperature is 100-180℃, such as 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, etc., and the drying time is 7-9 hours, such as 7 hours, 8 hours, 9 hours, etc.

[0041] Preferably, the first mixing, the second mixing, and the third mixing are all carried out in a planetary mixer.

[0042] Preferably, the rotation speed of the first mixing is 10 to 30 rpm, such as 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, etc., and the mixing time of the first mixing is 10 to 20 minutes, such as 10 minutes, 15 minutes, 20 minutes, etc.

[0043] Preferably, the rotation speed of the second mixing is 30 to 60 rpm, such as 30 rpm, 35 rpm, 40 rpm, 45 rpm, 50 rpm, 55 rpm, 60 rpm, etc., and the time of the second mixing is 1 to 2 hours, such as 1 hour, 1.5 hours, 2 hours, etc.

[0044] Preferably, the temperature rise is to 80-130°C, such as 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, etc.

[0045] Preferably, the third mixing is performed under vacuum.

[0046] Preferably, the third mixing time is 1 to 2 hours, such as 1 hour, 1.5 hours, 2 hours, etc.

[0047] Thirdly, the present invention provides an application of the thermal grease as described in the first aspect in electronic devices.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects:

[0049] The thermal grease provided by this invention comprises a combination of organosilicon oil, silane coupling agent, powder treatment agent, and thermally conductive powder. Through the screening and synergistic compounding of specific components, especially the introduction of a single-terminal alkoxy-type silane coupling agent, powder treatment agent, and specific thermally conductive powder, the prepared thermal grease exhibits ultra-low thermal resistance and a yield stress matching the thermal resistance, resulting in good heat dissipation capacity and operability. The introduction of the single-terminal alkoxy-type silane coupling agent improves the compatibility between the thermally conductive powder and organosilicon oil, achieving highly uniform dispersion of the thermally conductive powder. Furthermore, it enhances the interfacial interaction between the thermally conductive powder and organosilicon oil, reducing lattice vibration mismatch and thus lowering the thermal resistance of the thermal grease. The introduction of the powder treatment agent further improves the uniform dispersion of the powder treatment agent and the thermally conductive powder in the organosilicon oil. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] Unless otherwise specified, the single-terminal alkoxy silane coupling agent used in the following embodiments and comparative examples of the present invention is FM-0815J.

[0052] Example 1

[0053] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0054] 0.4 parts dodecyltrimethoxysilane, 3 parts monoterminated alkoxy silane coupling agent, 16.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 100 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of dimethyl silicone oil.

[0055] The method for preparing the thermal grease includes the following steps:

[0056] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 100 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0057] (2) Add 0.4 parts of dodecyltrimethoxysilane and 16.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio, stir at 50 rpm for 1.5 hours, raise the temperature to 120°C, and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0058] Example 2

[0059] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0060] 0.4 parts dodecyltrimethoxysilane, 3 parts monoterminated alkoxy silane coupling agent, 14.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 98 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of dimethyl silicone oil.

[0061] The method for preparing the thermal grease includes the following steps:

[0062] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 98 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0063] (2) Add 0.4 parts of dodecyltrimethoxysilane and 14.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio, stir at 50 rpm for 1.5 hours, raise the temperature to 120°C, and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0064] Example 3

[0065] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0066] 0.4 parts dodecyltrimethoxysilane, 3 parts monoterminated alkoxy silane coupling agent, 14.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 98 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of phenyl silicone oil.

[0067] The method for preparing the thermal grease includes the following steps:

[0068] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 98 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0069] (2) Add 0.4 parts of dodecyltrimethoxysilane and 14.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio, stir at 50 rpm for 1.5 hours, raise the temperature to 120°C, and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0070] Example 4

[0071] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0072] 0.4 parts dodecyltrimethoxysilane, 3 parts monoterminated alkoxy silane coupling agent, 14.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 98 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s(25℃) phenyl silicone oil and 350mm 2 A mixture of dimethyl silicone oils at 25°C, with a mass ratio of 1:1.

[0073] The method for preparing the thermal grease includes the following steps:

[0074] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 98 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0075] (2) Add 0.4 parts of dodecyltrimethoxysilane and 14.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio, stir at 50 rpm for 1.5 hours, raise the temperature to 120°C, and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0076] Example 5

[0077] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0078] 0.35 parts dodecyltrimethoxysilane, 3.5 parts monoterminated alkoxy silane coupling agent, 14.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 98 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of dimethyl silicone oil.

[0079] The method for preparing the thermal grease includes the following steps:

[0080] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 98 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0081] (2) Add 0.35 parts of dodecyltrimethoxysilane and 14.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3.5 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio and stir at 50 rpm for 1.5 hours. Raise the temperature to 120°C and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0082] Example 6

[0083] This embodiment provides a thermal grease, the raw materials for which the thermal grease is prepared include the following components by weight:

[0084] 0.45 parts dodecyltrimethoxysilane, 2.5 parts monoterminated alkoxy silane coupling agent, 14.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 98 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of dimethyl silicone oil.

[0085] The method for preparing the thermal grease includes the following steps:

[0086] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 98 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0087] (2) Add 0.45 parts of dodecyltrimethoxysilane and 14.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 2.5 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio and stir at 50 rpm for 1.5 hours. Raise the temperature to 120°C and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0088] Example 7

[0089] The only difference between this embodiment and Embodiment 1 is that the spherical aluminum powder with an average particle size of 1.3 μm is replaced with an equal weight proportion of spherical aluminum powder with an average particle size of 5.4 μm.

[0090] Example 8

[0091] The only difference between this embodiment and Embodiment 1 is that the spherical aluminum powder with an average particle size of 5.4 μm is replaced with an equal weight proportion of spherical aluminum powder with an average particle size of 1.3 μm.

[0092] Comparative Example 1

[0093] This comparative example provides a yield stress type thermal grease, the raw materials for which the yield stress type thermal grease is prepared include the following components by weight:

[0094] 0.4 parts dodecyltrimethoxysilane, 3 parts monoterminated alkoxy silane coupling agent, 10.6 parts silicone oil, 20 parts spherical zinc oxide with an average particle size of 0.2 μm, 30 parts spherical alumina with an average particle size of 0.5 μm, 34 parts spherical aluminum powder with an average particle size of 1.3 μm, and 102 parts spherical aluminum powder with an average particle size of 5.4 μm; wherein, the silicone oil is 350 mm 2 / s (25℃) of dimethyl silicone oil.

[0095] The preparation method of the yield stress type thermal grease includes the following steps:

[0096] (1) 20 parts of spherical zinc oxide with an average particle size of 0.2 μm, 30 parts of spherical alumina with an average particle size of 0.5 μm, 34 parts of spherical aluminum powder with an average particle size of 1.3 μm and 102 parts of spherical aluminum powder with an average particle size of 5.4 μm were placed in a vacuum drying oven at 150℃ for 8 hours, and then naturally cooled to 25℃ for later use.

[0097] (2) Add 0.4 parts of dodecyltrimethoxysilane and 10.6 parts of silicone oil to a planetary mixer and stir at 20 rpm for 15 minutes. Then add thermally conductive powder and 3 parts of single-terminal alkoxy silane coupling agent to the planetary mixer according to the weight ratio, stir at 50 rpm for 1.5 hours, raise the temperature to 120°C, and continue stirring under vacuum for 1.5 hours. Finally, cool the material to 25°C and discharge it.

[0098] Comparative Example 2

[0099] The only difference between this comparative example and Example 1 is that the silane coupling agent (single-terminal alkoxy silane coupling agent) is replaced with an equal weight amount of KH560 (γ-glycidoxypropyltrimethoxysilane).

[0100] Comparative Example 3

[0101] The only difference between this comparative example and Example 1 is that the raw materials used in its preparation do not include the powder treatment agent (dodecyltrimethoxysilane).

[0102] Comparative Example 4

[0103] The only difference between this comparative example and Example 1 is that the spherical zinc oxide is replaced with an equal weight proportion of spherical aluminum oxide with an average particle size of 0.5 μm.

[0104] Comparative Example 5

[0105] The only difference between this comparative example and Example 1 is that the spherical alumina is replaced with an equal weight proportion of spherical zinc oxide with an average particle size of 0.2 μm.

[0106] The thermal greases provided in the examples and comparative examples were subjected to performance tests, and the test methods are as follows:

[0107] (1) Interface thermal resistance test:

[0108] The interfacial thermal resistance of the sample was tested using a steady-state method, with a resistance and conductivity meter as the testing instrument; the test equilibrium temperature was 80℃, and the test pressure was 50psi.

[0109] (2) Thermal conductivity test:

[0110] The thermal conductivity of the sample was tested using the transient method, and the testing instrument was a thermal constant analyzer; the test temperature was 25℃.

[0111] (3) Yield stress test:

[0112] The yield stress of the sample was tested using a rheometer. The sample was placed under a parallel plate with a diameter of 25 mm and tested using a shear stress scanning program in rotation mode. The shear stress changed logarithmically from 0 Pa to 1000 Pa at 25 °C.

[0113] The performance test results are shown in Table 1.

[0114] Table 1

[0115]

[0116]

[0117] As can be seen from Table 1, the thermal greases provided in the embodiments of the present invention all have ultra-low interfacial thermal resistance (0.019~0.049 K·cm). 2 / W, preferably 0.019~0.039K·cm 2It has a suitable yield stress (83.35 to 113.6 Pa, preferably 83.35 to 106.54 Pa) and the yield stress can match the interfacial thermal resistance.

[0118] Compared with Example 1, the thermal grease provided in Comparative Example 1 has significantly increased interfacial thermal resistance and yield stress; the thermal grease provided in Comparative Example 2 has increased interfacial thermal resistance and yield stress; the thermal grease provided in Comparative Example 3 has increased interfacial thermal resistance and yield stress; the thermal grease provided in Comparative Example 4 has significantly increased interfacial thermal resistance and yield stress; and the thermal grease provided in Comparative Example 5 has increased interfacial thermal resistance and yield stress.

[0119] The applicant declares that this invention illustrates the thermal grease, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A thermally conductive silicone grease, characterized in that, The raw materials for preparing the thermal grease, by weight, include the following components: 12-20 parts of silicone oil; 2-5 parts of silane coupling agent; 0.2~0.5 parts of powder treatment agent; 150-200 parts of thermally conductive powder; The silicone oil is selected from dimethyl silicone oil and / or phenyl silicone oil; the viscosity of the silicone oil at 25°C is 50~500 mm. 2 / s; The silane coupling agent includes a single-terminal alkoxy-type silane coupling agent; the single-terminal alkoxy-type silane coupling agent has the structure shown in formula (I): ； Where m is an integer between 30 and 40; The powder treatment agent includes dodecyltrimethoxysilane; The thermally conductive powder comprises 15-23 parts of spherical zinc oxide with an average particle size of less than 1 μm, 25-35 parts of spherical alumina with an average particle size of 0.3-2 μm, 30-36 parts of spherical aluminum powder with an average particle size of 1-3 μm, and 97-100 parts of spherical aluminum powder with an average particle size of 4-6 μm.

2. The thermal grease according to claim 1, characterized in that, The interfacial thermal resistance of the thermal grease is ≤0.04 K·cm. 2 / W.

3. A method for preparing thermally conductive silicone grease as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: The formulated amounts of organosilicon oil, silane coupling agent, powder treatment agent, and thermally conductive powder are mixed to obtain the thermally conductive silicone grease.

4. The preparation method according to claim 3, characterized in that, The preparation method includes the following steps: The formulated amounts of silicone oil and powder treatment agent are mixed for the first time, then thermally conductive powder and silane coupling agent are added, and the mixture is mixed for the second time. The mixture is then heated and mixed for the third time to obtain the thermally conductive silicone grease.

5. The preparation method according to claim 4, characterized in that, The thermally conductive powder is dried before being added.

6. The preparation method according to claim 5, characterized in that, The drying temperature is 100~180℃, and the drying time is 7~9 hours.

7. The preparation method according to claim 4, characterized in that, The first, second, and third mixing processes were all carried out in a planetary mixer.

8. The preparation method according to claim 4, characterized in that, The rotation speed for the first mixing is 10-30 rpm, and the mixing time for the first mixing is 10-20 minutes.

9. The preparation method according to claim 4, characterized in that, The second mixing speed is 30~60 rpm, and the second mixing time is 1~2 hours.

10. The preparation method according to claim 4, characterized in that, The temperature increase refers to raising the temperature to 80~130℃.

11. The preparation method according to claim 4, characterized in that, The third mixing is carried out under vacuum.

12. The preparation method according to claim 4, characterized in that, The third mixing time is 1 to 2 hours.

13. The application of the thermal grease as described in claim 1 or 2 in electronic devices.

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