A process for the preparation of a stable silica sol of high surface area and high activity

摘要

PROBLEM TO BE SOLVED: To provide a method for preparing a stable aqueous colloidal silica which is usefully applied to papermaking and has a surface area of 700 m²/g or more and an S-value of 20-50.;SOLUTION: The method for preparing stable aqueous colloidal silica includes: preparing a starting composition containing water, an alkali metal silicate in which the molar ratio of SiO₂ and an alkali metal oxide is 15:1 to 1:1 and the pH is 10 or higher, and an acid, wherein the weight ratio of the alkali metal silicate to the acid is 63 or more; then maintaining the temperature of the staring composition to be lower than 32°C (90°F); adding an aqueous silicic acid composition containing SiO₂ in an amount of 4.0-8.5 wt.% and having a controlled temperature to the starting composition while adjusting the addition amount; and removing water from the composition until the solid content on the basis of SiO₂ of the stable colloidal silica becomes 7-20 wt.%, as occasion demands.;COPYRIGHT: (C)2013,JPO&INPIT