Thermally conductive silicone composition and method of making the same

Abstract

The application provides a heat-conducting organic silicon composition and a preparation method thereof. The preparation raw materials of the heat-conducting organic silicon composition include 2-5 parts of organic silicon-based glue, 0.1-0.5 parts of a curing agent, 0.1-1 parts of a catalyst, 0.5-1 parts of a coupling agent and 94-97 parts of heat-conducting fillers, the heat-conducting fillers include first heat-conducting fillers and second heat-conducting fillers, the weight ratio of the first heat-conducting fillers and the second heat-conducting fillers is 30-60:20-50, the first heat-conducting fillers are diamonds, and the second heat-conducting fillers at least include aluminum nitride; and the preparation raw materials are stirred by using a homogenizer. The aluminum nitride is an atomic crystal and belongs to a diamond-like nitride, and the structural unit thereof is similar to a tetrahedron of the diamond, so that the diamond can have better compatibility with other components under the action of the aluminum nitride, and even without additional powder modification treatment on the diamond, the organic silicon composition with high filling, good fluidity and high heat conduction can still be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat-conducting materials, in particular to a heat-conducting silicone composition and a preparation method thereof. BACKGROUND

[0002] With the increasing integration of electronic devices, the heat-conducting performance of heat-dissipating materials is also required to be higher. Diamond micro-powder is a heat-conducting filler with high heat conduction and insulation, which can be used to prepare high-heat-conducting gels with a heat conductivity of 10 W or more. A small amount of diamond filling can obtain a higher heat conduction effect than pure aluminum oxide and aluminum nitride systems.

[0003] Diamond is mostly a rhombohedral polyhedron. Compared with conventional spherical or spherical heat-conducting powders, diamond has high cost and few surface functional groups, and is not easy to modify. Therefore, the compatibility with resins such as silicone is poor. At the same time, it is difficult to mix with general heat-conducting powders, and it is difficult to achieve the required high heat conductivity (10 W or more) while maintaining high flow.

[0004] Although some manufacturers have studied the use of diamond in heat-conducting silicone gels, the performance is not good. For example, when diamond is used as a heat-conducting filler alone, and the filling amount reaches 90 wt.%, the heat-conducting silicone composition prepared is in a scattered state, has very poor flowability, and the heat conduction is not more than 10 W. When diamond and aluminum oxide are mixed as heat-conducting fillers, and the filling amount reaches 90 wt.%, the heat-conducting silicone composition prepared is hard and has a heat conduction of not more than 12 W. There are also wet modification methods for the surface of diamond in the industry. For example, CN104119841A discloses a method for preparing a high-heat-conducting silicone grease by wet modification of diamond micro-powder. Although the modification can improve the compatibility of diamond with silicone resin, the method is complex, has high cost and high pollution, and the heat conductivity is not more than 10 W.

[0005] At present, the high-heat-conducting paste used on the market is mostly an aluminum nitride or aluminum oxide system. Due to the high cost, difficult processing and poor compatibility with resins of diamond, its application in heat-dissipating interface materials is not widespread. SUMMARY

[0006] Based on the above problems, the purpose of the present application is to provide a heat-conducting silicone composition and a preparation method thereof. The heat-conducting silicone composition does not need to be modified, and has the characteristics of high filling, good flowability and high heat conduction.

[0007] To achieve the above object, the present application provides a heat-conducting organic silicon composition in one aspect, the preparation raw materials include 2-5 parts of organic silicon-based glue, 0.1-0.5 parts of curing agent, 0.1-1 parts of catalyst, 0.5-1 parts of coupling agent and 94-97 parts of heat-conducting filler, the heat-conducting filler includes first heat-conducting filler and second heat-conducting filler, and the weight ratio of the first heat-conducting filler and the second heat-conducting filler is 30-60:20-50, the first heat-conducting filler is diamond, the second heat-conducting filler includes at least aluminum nitride, and the preparation raw materials are stirred by a homogenizer.

[0008] In the technical scheme adopted by the present application, the filling amount of the heat-conducting filler is relatively high, more than 90wt.%. The heat-conducting filler includes diamond and aluminum nitride, both of which are high-heat-conducting materials, so that the heat-conducting organic silicon composition prepared has a relatively high heat-conducting coefficient. The aluminum nitride is an atomic crystal and belongs to a diamond-like nitride, and its structural unit is similar to the tetrahedron of diamond, so that the diamond can have better compatibility with other components under the action of the aluminum nitride, and under the high-speed stirring of the homogenizer, the glue generates heat by friction, and the coupling agent and the surface functional groups of the filler react with each other, so that even if the diamond is not subjected to additional powder modification treatment, the organic silicon composition with high filling, good fluidity and high heat conduction can still be obtained.

[0009] As one technical scheme of the present application, the organic silicon-based glue can be but is not limited to 2 parts, 3 parts, 4 parts or 5 parts. The curing agent can be but is not limited to 0.1 part, 0.2 part, 0.3 part, 0.4 part or 0.5 part. The catalyst can be but is not limited to 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 1.0 part. The coupling agent can be but is not limited to 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 1.0 part. The heat-conducting filler can be but is not limited to 94 parts, 95 parts, 96 parts or 97 parts.

[0010] As one technical scheme of the present application, the weight ratio of the first heat-conducting filler and the second heat-conducting filler can be but is not limited to 30:20, 30:30, 30:40, 30:50, 40:20, 40:30, 40:40, 40:50, 50:20, 50:30, 50:40, 50:50, 60:20, 60:30, 60:40 or 60:50.

[0011] As a technical solution of the present application, the silicone-based adhesive is a siloxane polymer containing vinyl groups. Preferably, the silicone-based adhesive is a siloxane polymer containing vinyl end groups, i.e., the main chain is siloxane, one end is vinyl, and the other end is alkoxy. The viscosity of the siloxane polymer is 10-200 mPas, and the content of vinyl groups in the silicone-based adhesive is 0.1-3.0 wt.%. For example, the content of vinyl groups in the silicone-based adhesive can be, but is not limited to, 0.1 wt.%, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, or 3.0 wt.%. As a technical solution of the present application, the viscosity of the silicone-based adhesive is 10-200 mPas. For example, the viscosity of the silicone-based adhesive can be, but is not limited to, 10 mPas, 30 mPas, 50 mPas, 80 mPas, 100 mPas, 130 mPas, 150 mPas, 180 mPas, or 200 mPas.

[0012] As a technical solution of the present application, the curing agent is a hydrosiloxane polymer, and the hydrogen content is 0.08-0.7 wt.%. For example, the hydrogen content can be, but is not limited to, 0.08 wt.%, 0.10 wt.%, 0.20 wt.%, 0.30 wt.%, 0.40 wt.%, 0.50 wt.%, 0.60 wt.%, or 0.70 wt.%. The hydrogen in the hydrosiloxane polymer can be an end hydrogen group or a side hydrogen group.

[0013] As a technical solution of the present application, the catalyst is a platinum gold catalyst. Preferably, the catalyst is a microencapsulated platinum gold catalyst. This catalyst has low reactivity at room temperature, can prolong the operation time, and the compound can be stored at low temperature for a long time.

[0014] As a technical solution of the present application, the coupling agent is a cage structure silane coupling agent and / or a linear structure silane coupling agent. Preferably, the coupling agent is a monoalkoxysiloxane, a bisalkoxysiloxane, or a trialkoxysiloxane, or an alkoxysiloxane containing a carboxyalkyl group or a vinyl group. More preferably, the coupling agent is n-dodecyltrimethoxysilane and / or n-dodecyldiethoxysilane.

[0015] As a technical solution of the present application, the second heat-conducting filler further includes aluminum oxide and / or zinc oxide.

[0016] As a technical solution of the present application, the particle size of the diamond is 100-180 μm, and as an example, the particle size of the diamond can be but is not limited to 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm. The particle size of the aluminum nitride is 1-150 μm, preferably 1-20 μm, or 80-150 μm. As an example, the particle size of the aluminum nitride can be but is not limited to 1 μm, 10 μm, 20 μm, 30 μm, 50 μm, 70 μm, 90 μm, 100 μm, 120 μm, 140 μm, 150 μm. The particle size of the aluminum oxide is 0.1-10 μm, preferably 2-10 μm, or 0.3-1 μm. As an example, the particle size of the aluminum oxide can be but is not limited to 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm. The particle size of the zinc oxide is 0.2-1 μm, and as an example, the particle size of the zinc oxide can be but is not limited to 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm.

[0017] Another aspect of the present application provides a preparation method of the heat-conducting silicone composition, comprising the steps of: stirring and dispersing the silicone-based glue, the curing agent, the coupling agent and the heat-conducting filler in a homogenizer, vacuum stirring, adding the catalyst after cooling, and vacuum stirring again.

[0018] As a technical solution of the present application, the stirring speed in the homogenizer is 1000-3000 r / min, and as an example, the stirring speed can be but is not limited to 1000 r / min, 1200 r / min, 1400 r / min, 1600 r / min, 1800 r / min, 2000 r / min, 2200 r / min, 2400 r / min, 2600 r / min, 2800 r / min, 3000 r / min. DETAILED DESCRIPTION

[0019] To better illustrate the purpose, technical solution and beneficial effects of the present application, the present application will be further described below in combination with specific examples. It should be noted that the following implementation of the method is a further explanation and description of the present application, and should not be regarded as a limitation of the present application.

[0020] Example 1

[0021] The heat conductive silicone composition of this example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 1.0 wt.%, viscosity: 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 1-10 μm), and 15 g of zinc oxide (particle size: 0.2-0.5 μm) in a plastic tank, stirring at a speed of 2000 r / min for 3 times, manually stirring with a spatula, vacuumizing, stirring at a high speed for 3 times at a speed of 2000 r / min, covering the tank after the stirring, placing the tank in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, stirring with a spatula, vacuumizing, stirring at a speed of 1500 r / min for 2 times, and collecting the product after the temperature is lowered to room temperature.

[0022] The heat conductive silicone composition of this example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 1.0 wt.%, viscosity: 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 1-10 μm), and 15 g of zinc oxide (particle size: 0.2-0.5 μm) in a plastic tank, stirring at a speed of 2000 r / min for 3 times, manually stirring with a spatula, vacuumizing, stirring at a high speed for 3 times at a speed of 2000 r / min, covering the tank after the stirring, placing the tank in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, stirring with a spatula, vacuumizing, stirring at a speed of 1500 r / min for 2 times, and collecting the product after the temperature is lowered to room temperature.

[0023] Example 2

[0024] The heat conductive silicone composition of this example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 1.0 wt.%, viscosity: 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 1-10 μm), and 15 g of zinc oxide (particle size: 0.2-0.5 μm) in a plastic tank, stirring at a speed of 2000 r / min for 3 times, manually stirring with a spatula, vacuumizing, stirring at a high speed for 3 times at a speed of 2000 r / min, covering the tank after the stirring, placing the tank in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, stirring with a spatula, vacuumizing, stirring at a speed of 1500 r / min for 2 times, and collecting the product after the temperature is lowered to room temperature.

[0025] The heat conductive silicone composition of this example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 1.0 wt.%, viscosity: 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 1-10 μm), and 15 g of zinc oxide (particle size: 0.2-0.5 μm) in a plastic tank, stirring at a speed of 2000 r / min for 3 times, manually stirring with a spatula, vacuumizing, stirring at a high speed for 3 times at a speed of 2000 r / min, covering the tank after the stirring, placing the tank in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, stirring with a spatula, vacuumizing, stirring at a speed of 1500 r / min for 2 times, and collecting the product after the temperature is lowered to room temperature.

[0026] Example 3

[0027] The heat conductive silicone composition of the present example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 2.0 wt.%, viscosity: 50 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.50 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyl diethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 10-20 μm), and 15 g of zinc oxide (particle size: 0.3-0.5 μm) in a plastic tank, stirring at a speed of 3000 r / min for 3 times, manually stirring with a spatula until uniform, vacuumizing and stirring at a speed of 2500 r / min for 3 times, covering the tank after completion, and storing in a refrigerator for 5 min. Then, 0.1 g of encapsulated platinum catalyst is added, stirred at a speed of 2000 r / min, and stirred with a spatula until uniform. After vacuumizing and stirring at a speed of 2000 r / min for 3 times, the mixture is left to stand until the temperature decreases to room temperature, and the product is collected.

[0028] The heat conductive silicone composition of the present example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 2.0 wt.%, viscosity: 50 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.50 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyl diethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 10-20 μm), and 15 g of zinc oxide (particle size: 0.3-0.5 μm) in a plastic tank, stirring at a speed of 3000 r / min for 3 times, manually stirring with a spatula until uniform, vacuumizing and stirring at a speed of 2500 r / min for 3 times, covering the tank after completion, and storing in a refrigerator for 5 min. Then, 0.1 g of encapsulated platinum catalyst is added, stirred at a speed of 2000 r / min, and stirred with a spatula until uniform. After vacuumizing and stirring at a speed of 2000 r / min for 3 times, the mixture is left to stand until the temperature decreases to room temperature, and the product is collected.

[0029] Comparative Example 1

[0030] The heat conductive silicone composition of the present example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 2.0 wt.%, viscosity: 50 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.50 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyl diethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 10-20 μm), and 15 g of zinc oxide (particle size: 0.3-0.5 μm) in a plastic tank, stirring at a speed of 3000 r / min for 3 times, manually stirring with a spatula until uniform, vacuumizing and stirring at a speed of 2500 r / min for 3 times, covering the tank after completion, and storing in a refrigerator for 5 min. Then, 0.1 g of encapsulated platinum catalyst is added, stirred at a speed of 2000 r / min, and stirred with a spatula until uniform. After vacuumizing and stirring at a speed of 2000 r / min for 3 times, the mixture is left to stand until the temperature decreases to room temperature, and the product is collected.

[0031] The heat conductive silicone composition of the present example is prepared by mixing 2.86 g of vinyl silicone oil (vinyl content: 2.0 wt.%, viscosity: 50 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content: 0.50 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyl diethoxysilane, 52.6 g of diamond (particle size: 150-160 μm), 24.6 g of aluminum nitride (particle size: 10-20 μm), and 15 g of zinc oxide (particle size: 0.3-0.5 μm) in a plastic tank, stirring at a speed of 3000 r / min for 3 times, manually stirring with a spatula until uniform, vacuumizing and stirring at a speed of 2500 r / min for 3 times, covering the tank after completion, and storing in a refrigerator for 5 min. Then, 0.1 g of encapsulated platinum catalyst is added, stirred at a speed of 2000 r / min, and stirred with a spatula until uniform. After vacuumizing and stirring at a speed of 2000 r / min for 3 times, the mixture is left to stand until the temperature decreases to room temperature, and the product is collected.

[0032] Comparative Example 2

[0033] The raw materials of the heat conductive silicone composition of the present example include 2.86 g of vinyl silicone oil (vinyl content 2.0 wt.%, viscosity 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size 150-160 μm), 24.6 g of alumina (particle size 5-10 μm), and 15 g of zinc oxide (particle size 0.5-0.7 μm).

[0034] The preparation method of the heat conductive silicone composition of the present example includes: placing the vinyl silicone oil, hydrogen-containing silicone oil, n-dodecyltrimethoxysilane, diamond, aluminum nitride, and zinc oxide in a plastic tank, stirring at a speed of 2000 r / min for 3 times, then stirring uniformly by hand, then vacuumizing and stirring at a speed of 2000 r / min for 3 times, covering the tank after completion, placing in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, then stirring uniformly by hand, vacuumizing and stirring at a speed of 1500 r / min for 2 times, and then collecting the product after the temperature drops to room temperature.

[0035] Comparative Example 3

[0036] The raw materials of the heat conductive silicone composition of the present example include 2.86 g of vinyl silicone oil (vinyl content 2.0 wt.%, viscosity 20 mPas), 0.34 g of hydrogen-containing silicone oil (hydrogen content 0.20 wt.%), 0.1 g of encapsulated platinum catalyst, 1.0 g of n-dodecyltrimethoxysilane, 52.6 g of diamond (particle size 150-160 μm), 24.6 g of alumina (particle size 5-10 μm), and 15 g of zinc oxide (particle size 0.5-0.7 μm).

[0037] The preparation method of the heat conductive silicone composition of the present example includes: placing the vinyl silicone oil, hydrogen-containing silicone oil, n-dodecyltrimethoxysilane, diamond, aluminum nitride, and zinc oxide in a plastic tank, stirring at a speed of 2000 r / min for 3 times, then stirring uniformly by hand, then vacuumizing and stirring at a speed of 2000 r / min for 3 times, covering the tank after completion, placing in a refrigerator for 3 min, adding the encapsulated platinum catalyst, stirring at a speed of 1500 r / min, then stirring uniformly by hand, vacuumizing and stirring at a speed of 1500 r / min for 2 times, and then collecting the product after the temperature drops to room temperature.

[0038] The heat conductive silicone compositions prepared in Examples 1-3 and Comparative Examples 1-3 were tested for extrusion coefficient and heat conductivity coefficient, and the results are shown in Table 1.

[0039] The extrusion coefficient test requires the weight of the glue flowing out within 1 minute using a 30cc syringe, the inner diameter of the syringe is 2.54mm, and the pressure is 90PSI.

[0040] The performance test results of the heat-conducting silicone compositions prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0041] Test item Thermal conductivity (W / m*K) Extrusion coefficient (g / min) Example 1 17.6 23 Example 2 15.1 15 Example 3 13.8 8 Comparative Example 1 12.7 6 Comparative Example 2 11.3 3 Comparative Example 3 10.1 5

[0042] As shown in Table 1, the heat-conducting silicone compositions of Examples 1-3 have higher thermal conductivity and extrusion coefficient than Comparative Examples 1-3, which indicates that the preparation of the raw materials in the present application includes diamond and aluminum nitride as the heat-conducting filler, and the use of a homogenizer for stirring can make the prepared heat-conducting silicone composition have higher thermal conductivity and better flowability.

[0043] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it is not limited to the examples listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the present application.

Claims

1. A method for producing a heat-conducting silicone composition, characterized by, The raw materials for preparing the heat-conducting silicone composition include 2-5 parts of silicone gum, 0.1-0.5 parts of curing agent, 0.1-1 parts of catalyst, 0.5-1 parts of coupling agent and 94-97 parts of heat-conducting filler, the heat-conducting filler includes first heat-conducting filler and second heat-conducting filler, the weight ratio of the first heat-conducting filler to the second heat-conducting filler is 30-60:20-50, the first heat-conducting filler is diamond, the second heat-conducting filler includes at least aluminum nitride, the particle size of the diamond is 100-180 μm, the particle size of the aluminum nitride is 1-150 μm, and the preparation method comprises the following steps: stirring and dispersing the silicone gum, the curing agent, the coupling agent and the heat-conducting filler in a homogenizer, then adding the catalyst after vacuum stirring and cooling, and then vacuum stirring again.

2. The method for producing the heat-conducting silicone composition according to claim 1, characterized by, The silicone gum is a siloxane polymer containing vinyl groups.

3. The method for producing the thermally conductive silicone composition according to claim 1, characterized by, The silicone gum is a siloxane polymer containing vinyl end groups.

4. The method for producing a heat-conducting silicone composition according to claim 2 or 3, characterized by, The content of vinyl groups in the silicone gum is 0.1-3.0 wt.%.

5. The method for producing the thermally conductive silicone composition according to claim 1, characterized by, The curing agent is a hydrogen-containing siloxane polymer, and the hydrogen content is 0.08-0.70 wt.%.

6. The method for producing the thermally conductive silicone composition according to claim 1, characterized by, The catalyst is a platinum-gold catalyst.

7. The method for producing the thermally conductive silicone composition according to claim 1, characterized by, The coupling agent is a cage structure silane coupling agent and / or a linear structure silane coupling agent.

8. The method for producing the thermally conductive silicone composition according to claim 1, characterized by, The second heat-conducting filler further includes aluminum oxide and / or zinc oxide.

9. The method for producing the thermally conductive silicone composition according to claim 8, characterized by, The particle size of the aluminum oxide is 0.1-10 μm, and the particle size of the zinc oxide is 0.2-1 μm.