METHOD FOR PRODUCING PURIFIED SILICIC ACID ALKALI AQUEOUS SOLUTION AND SILICA SOL

摘要

There is provided a method for producing an alkali silicate aqueous solution containing a reduced amount of foreign substance of plate-like fine particles and a method for producing a silica sol containing a reduced amount of foreign substance of plate-like fine particles. A method for producing an alkali silicate aqueous solution fulfilling the following condition (1): (1) the existing amount of plate-like fine particles having a length of one side of 0.2 to 4.0 µm and a thickness of 1 to 100 nm is determined to be 0 to 30% in accordance with a measurement method A, the method for producing an alkali silicate aqueous solution characterized by comprising the steps of: adjusting a silica concentration of an alkali silicate aqueous solution to 0.5 to 10.0% by mass; and filtering the alkali silicate aqueous solution through a filter having a removal rate of particles with a primary particle size of 1.0 µm of 50% or more.