| abstract |
(57) [Summary] [Object] To provide a method for efficiently producing an elongated silica sol. [Structure] The following steps (a), (b) and (c): (A) a step of adding an aqueous solution of a water-soluble calcium salt, a magnesium salt or a mixture thereof to a colloidal aqueous solution of activated silicic acid, (b) a step of adding an alkaline substance to the aqueous solution obtained in the step (a), and ( c) Part or all of the mixture obtained in step (b) is heated to 60 ° C. or higher to obtain a heel liquid, and a part of the mixture obtained in step (b) or a mixture prepared separately in step (b) is used. As the feed liquid, by adding the feed liquid to the heel liquid and evaporating water during the addition, SiO 2 A process for producing an elongated silica sol, which comprises a step of concentrating to a concentration of 6 to 30% by weight. |