| 摘要 |
PROBLEM TO BE SOLVED: To stably obtain silica particles far excellent in moisture absorption by specifying an apparent density and a bulk density of the silica particles obtained by a sol-gel method. SOLUTION: This silica particle has 1.70-0.80g/cm<3> apparent density, 0.70-0.80g/cm<3> bulk density and >=10% coefficient of moisture absorption. Though the characteristic values are not specifically limited except the apparent density and the bulk density, e.g. the average particle size is preferably 0.1-3μm. The production method of silica particles is to add an alkoxysilane to an aqueous alkaline solution and obtain a water dispersion of silica particles through hydrolysis and condensation. It is preferable to obtain silica particles having large particle sizes of >=1μm by dispersing seed particles in the aqueous alkali solution in advance. The obtained aqueous dispersion of the silica particles is condensed preferably by giving a mechanical mixing force. Further, nonreacted alkoxysilane is hydrolyzed by adding water to the concentrated system. Then, the concentrate is dried and baked to obtain the objective silica particles.
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