SULFONIC ACID-MODIFIED AQUEOUS ANIONIC SILICA SOL AND METHOD FOR PRODUCING SAME

摘要

Disclosed is a sulfonic acid-modified aqueous anionic silica sol which is highly stable under acidic conditions, while having a low metal impurity content and good filtration properties. Also disclosed is a method for producing the sulfonic acid-modified aqueous anionic silica sol. Specifically disclosed are: a method for producing a sulfonic acid-modified aqueous anionic silica sol, wherein a silane coupling agent having a functional group which can be chemically converted into a sulfonic acid group is added to colloidal silica, and then the functional group is converted into a sulfonic acid group; and a sulfonic acid-modified aqueous anionic silica sol which is obtained by the method and has a zeta-potential of not more than -15 mV in an acidic environment with a pH of 2 or more.