| abstract |
There is provided colloidal silica particles comprising at least one polyvalent metal element M selected from a group consisting of iron, aluminum, zinc, zirconium, titanium, tin, and lead in an average content of 0.001 to 0.02 in terms of an M/Si molar ratio, and having an average primary particle diameter of 5 to 40 nm, wherein the content of the polyvalent metal element M present in an outermost layer of the colloidal particles is 0 to 0.003 atom per square nanometer (nm 2 ) of a surface area of the colloidal particles; and a silica sol that the colloidal silica particles are dispersed in an organic solvent, a silica sol that the colloidal silica particles are dispersed in a polymerizable compound, and a silica sol that the colloidal silica particles are dispersed in a dicarboxylic anhydride. The colloidal silica particles do not cause decomposition, discoloration and the like of an organic compound even when they are dispersed in the organic compound, although the prior colloidal silica particles have caused them due to the action of solid acid on the surface thereof. The silica sols of the present invention do not cause decomposition, discoloration and the like of a resin even when they are mixed into the resin, and have good dispersion stability to a dispersion medium. |