Thixotropic heat conduction insulating sealant and preparation method thereof

Abstract

The invention discloses a thixotropic heat conduction insulating sealant which comprises base adhesive raw materials, including polydimethylsiloxane, a heat conduction filler and a thixotropic filler,wherein the heat conduction filler is a mixture of silicon micropowder and zinc oxide. As the silicon micropowder and the zinc oxide are compounded as the heat conduction filler, and nano calcium carbonate or hydrophobic gas-phase white carbon black are adopted as the thixotropic filler, the heat conduction coefficient is up to 1.0W / m.K, and the density is not higher than 1.8g / cm<3>; the mechanical property is good, the elongation at break is greater than 150%, and the tension strength is greater than 1.8MPa; and good thixotropy is achieved, and the sagging degree is smaller than 1.0mm, and acuring depth within 24 hours is greater than 1.5mm. The invention further discloses a preparation method of the thixotropic heat conduction insulating sealant.

Description

technical field [0001] The invention relates to a sealant, in particular to a thixotropic heat-conducting and insulating sealant and a preparation method thereof. Background technique [0002] Based on the principle of economical practicability, in practical applications, the products that can be seen on the market, the existing heat-conducting and insulating room temperature vulcanized silicone sealants mainly use alumina as the main filling material, and may be mixed with zinc oxide, magnesium oxide and other raw materials. The existing room temperature vulcanized thermally conductive insulating silica gel mainly uses alumina as the main filler, and thermally conductive insulating fillers such as alumina and zinc oxide have a relatively large proportion. However, thermally conductive silicone rubber needs a large amount of filling to obtain a relatively ideal heat conduction effect. The proportion of heat-conducting silica gel has risen sharply. For example, when the heat-...

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Problems solved by technology

The existing room temperature vulcanized thermally conductive insulating silica gel mainly uses alumina as the main filler, and thermally conductive insulating fillers such as alumina and zinc oxide have a relatively large proportion. However, thermally conductive silicone rubber needs a large amount of filling to obtain a relatively ideal heat conduction effect. The proportion of heat-conducting silica gel has risen sharply. For example, when the heat-conducting glue is filled with alumina, when the thermal conductivity reaches 1.0W / m·K, the specific gravity will reach 2.5g / cm 3 Above, this greatly limits the application in fields with high lightweight requirements such as new energy batteries

[0003] In addition, the consequences of filling a large amount of metal alumina will seriously damage the mechanical properties of the sealant. The elongation at break of ordinary silica gel can reach 500%. When the thermal conductivity of the sealant filled with alumina reaches 1.0W / m K , the elongation at break will drop sharply below 100%, or even only about 50%. Affected by this, the mechanical strength will also drop significantly, which seriously weakens the advantages of shock resistance and fatigue resistance of the silicone material itself.

[0004] The metal oxide itself has a large specificity, which will seriously damage the thixotropy of the sealant. In order to improve the thixotropy of the sealant, it is necessary to fill more nano-calcium carbonate as a thixotropic filler. The more nano-calcium carbonate is filled, the better the thermal conductivity. The more severe the damage, in turn, the more alumina is filled to maintain thermal conductivity, the higher the density, the worse the mechanical properties

If it is filled with thermally conductive and insulating materials such as boron nitride, silicon nitride, and aluminum nitride recorded in the literature, these materials can easily cost several hundred yuan per kilogram, and the economy determines that large-scale application is impossible.

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