PRODUCTION OF SILICA SOL CONTAINING SILICA PARTICLE HAVING LARGE PARTICLE DIAMETER

摘要

PROBLEM TO BE SOLVED: To produce a silica sol comprising silica particles having a uniform particle diameter and a specific average particle diameter of a sharp particle size distribution by carrying out a precise filtration under pressure using a precise filtration membrane having a specified nominal pore diameter as the final step of a concentration process. ;SOLUTION: A precise filtration membrane having 0.05-0.5 μm nominal pore diameter is used as the precise filtration membrane. The material is not especially limited; however, an organic membrane such as collodion or an inorganic membrane such as graphite is used. The pressure may be set at a withstanding pressure of the precise filtration membrane used or below and is usually about 2 atm. The operating temperature is usually 50-100°C. The silica sol concentration to be fed is ≤4 wt.% expressed in terms of SiO2 concentration. The form of the precise filtration membrane is not especially limited; however, a flat membrane, a tubular membrane, a hollow fiber, a spiral membrane or the like is used. The resultant silica sol comprises large-particle diameter silica particles having a uniform particle diameter and 100-500 nm average particle diameter of a sharp particle size distribution.;COPYRIGHT: (C)2000,JPO