| 摘要 |
PROBLEM TO BE SOLVED: To produce an aqueous silica sol containing lesser impurities such as alkali metals or multivalent metals, and in particular lesser coagulated gels by adding an alkoxysilane to an acidic aqueous solvent to subject the alkoxysilane to hydrolysis treatment and to form silicic acid monomer and further adding the silicic acid monomer to a basic solvent to subject the silicic acid monomer to polymerization treatment. SOLUTION: This production process comprises adding an alkoxysilane to an acidic aqueous solvent to subject the alkoxysilane to hydrolysis treatment and to form silicic acid monomer and further adding the silicic acid monomer to a basic aqueous solvent to subject the silicic acid monomer to polymerization treatment and to produce the objective aqueous silica sol, wherein: the alcohol formed as a by-product in the hydrolysis treatment is preferably removed in the polymerization treatment; also preferably, the polymerization treatment is performed in such a state that the pH of the system is 8.5 to 11.5, while adjusting the volume of the system so as to be >=95% of the initial volume of the system in this polymerization treatment; as the alkoxysilane, tetraethoxysilane, tetramethoxysilane, methoxytriethoxysilane, or the like, is used; and as the basic aqueous solvent, ethylenediamine, diethylenetriamine, triethylenetetramine, or the like, is used.
|
