| abstract |
(57) [Summary] [Problem] To be excellent in production efficiency, fast in particle growth rate, A silica sol and a silica-based composite oxide sol having a uniform and stable particle diameter are produced. SOLUTION: An alkali silicate aqueous solution is added to a core particle dispersion or an alkali silicate aqueous solution in the presence of an electrolyte to grow core particles, thereby producing a silica sol. In addition, in the presence of an electrolyte in a nuclear particle dispersion or an aqueous solution of an alkali silicate, An aqueous solution of an alkali silicate and an aqueous solution of a metal salt or a non-metal salt other than silicon are added to grow core particles, thereby producing a silica-based composite oxide sol. The electrolyte comprises a salt of a strong acid, and the ratio (E A ) of the number of equivalents (E A ) of the alkali in the supplied alkali silicate to the number of equivalents (E E ) of the electrolyte. / E E ) is preferably in the range of 0.5 to 8. After the addition of the alkali silicate aqueous solution, the mixture is aged in a temperature range of 40 to 150 ° C. for 10 minutes to 3 hours. The mixture was deionized to reduce the amount of residual anions to Si. The content may be 0.01% by weight or less of O 2 . |