AMORPHOUS SILICA-BASED COMPOSITE PARTICLE AND ITS USE

PROBLEM TO BE SOLVED: To obtain an amorphous silica-based composite particle capable of effectively manifesting a plurality of functions at different steps by forming the composite particle out of a core of a particle comprising an amorphous silica, an amorphous silica alumina or an amorphous aluminosilicate in a fixed form, and a shell out of an aggregate comprising amorphous silica fine particles. SOLUTION: This amorphous silica-based composite particle is constituted of a core A of a fixed-form particle having 0.5-100 μm particle diameter and selected from an amorphous silica, an amorphous silica alumina or an amorphous aluminosilicate, or an aggregate thereof, and a shell B covering the fixed- form particle or the aggregate thereof, and formed out of an aggregate comprising amorphous silica fine particles. Preferably, the amorphous silica-based composite particle forms a pomegranate-shaped structure having the shell B filled with the fixed-form particle A. The weight ratio of the core A of the fixed-form particle or the aggregate thereof to the shell B of the amorphous silica fine particles is preferably regulated so as to be (20:80) to (80:20) expressed in terms of silica weight based on SiO2 .