Denki Kagaku Kogyo Kabushiki Kaisha

Mitsuyoshi Iwasa

Yasuhisa Nishi

Shuji Sasaki

Yukio Sakaguchi

Hirofumi Simazoe

Shinji Yamano

The present invention provides ceramic powder capable of being incorporated into rubber or a resin for the preparation of a composition, which shows excellent heat resistance and flame retardancy and which is used, for instance, as a semiconductor-sealing material. The ceramic powder has a multi-peak frequency distribution pattern having at least two peaks as a particle size distribution as determined using a laser diffraction-scattering type particle size-analyzer, wherein the maximum particle size for the first peak ranges from 40 to 80 &#x3bc;m and that for the second peak ranges from 3 to 8 &#x3bc;m and wherein the rate of the particles having a particle size of not less than 20 &#x3bc;m and less than 40 &#x3bc;m is not more than 20% by mass (inclusive of 0% by mass).

Ceramic powder and applications thereof

The present invention herein provides fine inorganic hollow powder having a high hollowness rate, which can be incorporated into, for instance, a low dielectric rubber or resin composition. The inorganic hollow powder has an average hollowness rate of higher than 70% by volume and an average particle size ranging from 3 to 20 &#x3bc;m and the powder preferably has an average hollowness rate ranging from 75 to 85% by volume, an average particle size ranging from 5 to 15 &#x3bc;m, a maximum particle size of not more than 25 &#x3bc;m, a specific surface area of not more than 10 m/g, an average sphericity degree of not less than 0.90 and a purity of not less than 99% by mass. The inorganic hollow powder can be prepared by a method comprising the steps of forming a flame using a burner provided with at least a triplet-tubular portion comprising, in order from the outermost side, a combustion-improving gas-supply pipe, a combustible gas-supply pipe and an inorganic raw powder-supply pipe assembled together; injecting, into the flame at a high discharge speed, inorganic raw powder having a specific particle size through the inorganic raw powder-supply pipe, while the powder is entrained with a carrier gas having a specific relative humidity, to thus subject the powder to a heat-treatment.

Inorganic hollow particle, process for producing the same, and composition containing the same

A silica filler containing from 30 to 90 wt % of particles having a particle size of at least 30 .mu.m, wherein the roundness of the particles having a particle size of at least 30 .mu.m, is from 0.83 to 0.94.

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Omuta, Japan

Mitsuyoshi Iwasa