INORGANIC HOLLOW PARTICLE, PROCESS FOR PRODUCING THE SAME, AND COMPOSITION CONTAINING THE SAME

摘要

Inorganic hollow particles for incorporation into low-dielectric rubber or resin compositions, etc., which are ultrafine and have a high percentage of hollowness. The inorganic hollow particles have an average percentage of hollowness exceeding 70 vol.% and an average particle diameter of 3-20 µm. They preferably have an average percentage of hollowness of 75-85 vol.%, average particle diameter of 5-15 µm, maximum particle diameter of 25 µm or smaller, specific surface area of 10 m²/g or smaller, average degree of sphericity of 0.90 or higher, and purity of 99 mass% or higher. The inorganic hollow particles can be produced by: forming a flame using a burner having at least a triple-tube part comprising a combustion-supporting-gas feed pipe, a combustible-gas feed pipe, and an inorganic-raw-material-powder feed pipe which have been arranged in this order from the outside; and injecting an inorganic raw-material powder of a specific particle size into the flame by ejecting the powder from the inorganic-raw-material-powder feed pipe of the burner at a high ejection rate together with a carrier gas having a specific relative humidity to thereby conduct a heat treatment.