Preparation of silica sol

摘要

A method for producing a silica sol containing less than 200 ppm sodium having an average particle size of 2-110 nm, and a particle size distribution with a coefficient dispersion of 0.16-0.4. The silica sols are produced using a lower alkanolamine containing heal to which aliquots of silicic acid are added. The aliquots are added to maintain a substantially constant concentration of colloidal silica in the product. Subsequent to production, the sol may be concentrated by ultrafiltration. Preparation of low sodium silica sol utilizing a constant silica technique by heating the initial heel to 94 DEG +/-4 DEG C. and adding additional silica maintaining constant total silica. The stabilization is effected with an alkanolamine.