JPH0369953B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a thermosetting heat-resistant adhesive having excellent thermal conductivity, electrical insulation and heat resistance. [Technical background of the invention and its problems] Conventionally, when bonding a ceramic heater to a pressure cooker or a heat-retaining cooker that repeats cycles of heating and cooling to room temperature, thermal conductivity, electrical insulation, and heat resistance are required. An adhesive with both properties is required. Conventionally, heat-resistant adhesives containing SiO ₂ , Fe ₂ O ₃ , Al ₂ O _3, etc. in silicone rubber are known, but while they have excellent electrical insulation properties, they have poor thermal conductivity. It has the disadvantage of being low at 0.86kcal/mhr℃. Adhesive crease containing 95% ZnO in silicone oil is also known, but like the above, it has the disadvantage of a low thermal conductivity of 0.54 kcal/mhr°C.
Furthermore, heat-resistant adhesives with excellent thermal conductivity of 8 to 10 kcal/mhr°C are also known, but because they contain metal powder, they have a specific resistance of 8.4 Ω/cm and have poor electrical insulation properties. By the way, to improve only the thermal conductivity, it is sufficient to add metal powder such as Cu, Al, Ag, etc. For example, the thermal conductivity of synthetic resin is generally 0.
At 0.2kcal/mhr℃, Cu is 338kcal/mhr℃, Al is
194kcal/mhr℃, Fe 61.2kcal/mhr℃.
Therefore, if metal powder is added to the synthetic resin, the thermal conductivity will be improved, but the electrical insulation properties will be reduced, making it unusable. In addition, when flame-retardant inorganic adhesives are mixed with substances with excellent electrical insulation and thermal conductivity, they are susceptible to moisture, allowing moisture to pass through easily, impairing electrical insulation properties, and causing long-term effects. There are some drawbacks that make it unusable. Prior to the present invention, our company had incorporated thermosetting resins into thermosetting resins.
Although we have developed adhesives containing AlN, they have severe reactivity with moisture, which can be quite disadvantageous in some environments. [Purpose of the Invention] This invention was made to eliminate the above-mentioned drawbacks, and it has a structure that can withstand repeated cycles of heating and cooling, has excellent thermal conductivity, electrical insulation, and heat resistance, and can also withstand long-term use. The aim is to provide adhesives that can be obtained. [Summary of the Invention] The present invention consists of aluminum nitride (aluminum nitride) in which a thermosetting synthetic resin is coated with a highly corrosion-resistant insulating layer 1 made of at least one of silicon nitride, aluminum oxide, and boron nitride on the surface as shown in FIG. AlN)
This is a heat-resistant adhesive containing grains 2. Here, as a thermosetting synthetic resin, diamino diphenyl methane (DDM) is used as a trifunctional epoxy resin.

[Embodiments of the invention]

Examples of the present invention will be described below. A solvent such as methyl ethyl ketone (MEK) is added to a thermosetting synthetic resin liquid such as epoxy resin, silicone varnish, phenolic resin, polyurethane, or acrylic resin to adjust the viscosity to an appropriate level, and then Si ₃ N ₄ or Al ₂ O ₃ is applied to the surface. A variety of heat-resistant adhesives were obtained by adding aluminum nitride powder coated with and stirring thoroughly. Each of the adhesives thus obtained was degassed in vacuum to remove the solvent, and then cured by heating to form a 1 cm ³ cube, and the thermal conductivity was measured. The measurement results are shown in Tables 1 to 5. Table 1 shows the relationship between the mixing ratio of composite aluminum nitride in epoxy resin (ELM-120) and thermal conductivity, Table 2 shows the relationship with silicon varnish (TSR-117), and Table 3 shows the relationship with silicon varnish (TSR-117).
The table shows the relationship with phenolic resin (Cemedine 120 heat curing type), Table 4 shows the relationship with polyurethane (Cemedine-700), and Table 5 shows the relationship with acrylic resin (Hardlock C). show. In addition, the weight in the table is g, the mixing ratio is weight%,
Thermal conductivity is expressed in kcal/mhr°C.

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〔Effect of the invention〕

As described above, the heat-resistant adhesive according to the present invention has (1) excellent thermal conductivity, and (2) constant heat resistance.
Can be maintained at temperatures above 150℃, (3) withstands heating and cooling cycles from room temperature to 150-200℃, (4) has no electrical conductivity as no metal powder is added, and (5) is water resistant and can withstand long-term use. , and (6) extremely good adhesion.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing aluminum nitride grains whose surfaces are coated with a highly corrosion-resistant insulating layer used in the present invention. 1... Insulating layer with high corrosion resistance, 2... Aluminum nitride grains.

Claims (1)

[Claims] 1. A heat-resistant adhesive comprising a thermosetting synthetic resin containing aluminum nitride grains coated with a highly corrosion-resistant insulating layer made of at least one of silicon nitride, aluminum oxide, and boron nitride.