Preparation method of highly dispersed graphene-based thermal conductive silica gel

Abstract

The present invention relates to a preparation method of a highly dispersed graphene-based thermal conductive silica gel. The preparation method comprises the following steps: (1) graphite oxide is added to water and ultrasonic stripping is conducted to form a graphene oxide aqueous suspension; aluminum salts are added to the graphene oxide aqueous suspension to be ultrasonically dispersed to forma solution A; a precipitant solution is prepared, a dispersing agent is also added to form a solution B; the solution A and solution B are mixed and stirred to obtain a gray precipitate, and then gray precipitate filtering, washing, drying and calcining are conducted to obtain a graphene / Al2O3 composite filler; (2) a coupling agent solution is prepared, the graphene / Al2O3 composite filler is added, and then stirring, filtering, washing and drying are conducted to obtain a coupling agent-modified graphene / Al2O3 composite filler; and (3) the coupling agent-modified graphene / Al2O3 composite filler is mixed with a silicone rubber matrix and an auxiliary agent, and then vulcanization is conducted to obtain the highly dispersed graphene-based thermal conductive silica gel. The preparation method can improve dispersibility of graphene as a thermally conductive filler and improve thermal conductivity.

Description

technical field [0001] The invention relates to the field of thermally conductive materials, in particular to a method for preparing highly dispersed graphene-based thermally conductive silica gel. Background technique [0002] With the continuous development of semiconductors and electronic components in the direction of miniaturization, light weight and high efficiency, the problem of thermal problems has intensified, and good heat dissipation measures are urgently needed to solve them. As an elastic material between the heat source and the radiator, thermal silica gel plays an important role in expelling air and accelerating heat dissipation. It has good heat dissipation, shock absorption, chemical corrosion resistance and wide service temperature (-90~250℃ ), can maintain elasticity and use stability in extreme and harsh environments, and is very suitable for elastic bonding, positioning, heat dissipation, insulation and Sealed for use. [0003] Thermally conductive si...

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Problems solved by technology

[0005] However, the current problems faced by graphene-based thermal silica gel are: 1. Graphene is very easy to agglomerate, and the formation of thermal conduction paths will be affected due to agglomeration inside the filling matrix. This is due to the large specific surface area of ​​graphene, which leads to its high surface energy, it is easy to entangle and agglomerate during the dispersion process, and it is difficult to form a uniform dispersion system with other materials. The fewer layers of graphene, the better its thermal conductivity, so the dispersion of graphene in the matrix seriously affects Thermal conductivity of graphene-based thermal silica gel

2. Graphene is used to fill thermal silica gel alone. There is a certain gap between the filler and the matrix interface. During the internal heat transfer process, the interface effect causes interface thermal resistance, which directly affects the thermal conductivity of the system.

3. Different materials, different sizes, and different dimensions of thermally conductive fillers are mixed with each other. The thermally conductive fillers prepared by virtue of the synergistic effect between thermally conductive fillers are conducive to improving the thermal conductivity of thermally conductive silica gel. However, existing research cannot fully utilize graphite. Synergistic mechanism between ene and other thermally conductive fillers

4. Among the aluminas with different shapes, the thermally conductive silica gel prepared by spherical alumina as a filler has the best thermal conductivity. The preparation methods of spherical alumina mainly include sol-gel method, drop ball method, template method, etc., using sol The spherical alumina prepared by the gel method has a wide range of particle sizes, high sphericity, and good dispersion, but the agglomeration is serious after sintering; the drop ball method is a further improvement on the process of the sol-emulsion-gel method. The alumina has high purity and the best dispersion, but the size range is narrow, and the particle size is usually large; the template method is suitable for the preparation of hollow spheres, which has high requirements for the template agent, many steps in the preparation process, and high cost

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