| 摘要 |
PROBLEM TO BE SOLVED: To provide a simple and efficient method for producing spherical silica particles of microsize by using an water-in-oil type emulsion obtained by solubilizing water or an aqueous solution and to obtain spherical silica particles of new structure prepared by the method. SOLUTION: The spherical silica particles of microsize have a core/shell structure with a concentration gradient structure in which the outer peripheral part is a shell, the central part is hollow and the shell is dense at the outside and is made coarser as it reaches the interior. This method for producing the spherical silica particles comprises mixing a concentrated mixed solution containing a tetraalkoxysilane in a low polar organic solvent as a continuous phase with water or an aqueous solution as a disperse phase and an anionic surfactant with stirring to form a water-in-oil type emulsion in which the water or the aqueous solution as the disperse phase is solubilized in the continuous phase in such a way that the water content of the water-in-oil type emulsion is increased, the solubilized water is adjusted to form two phase of combined water and free water and hydrolysis and condensation polymerization are carried out by the solubilized water of the emulsion as a reaction site. |
