Production methodological null description below of the silica sol which contains the silica particle of large

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a silica sol formed by dispersing a spherical large particle diameter colloidal silica having uniform particle diameter in a liquid medium. ;SOLUTION: A heel solution is prepared by mixing a water based silica sol ≥20nm in particle diameter with an alkali silicate aq. solution and/or an alkali aq. solution and adjusting the molar ratio of (total SiO₂)/M₂O (M is an alkali metal) in the mixed solution to 10-100. A feed solution is prepared by adjusting the water based silica sol to have 6-10nm particle diameter, 8-20wt.% SiO₂ concn and pH at 2-5. The heel solution is fed to a vessel and the feed solution is added in the heel solution while keeping the heel solution at ≥90°C to grow the particle diameter of the silica particle.;COPYRIGHT: (C)1997,JPO