| abstract |
Silica base for dentifrice having excellent transparency and prolonged stability, desired abrasive ability, specific surface area of 5 to 60 m2/g as measured according to the BET or CTAB method, with the difference therebetween being 40 m2/g or less, and having a refractive index of 1.42 to 1.45, which can be prepared by reacting an alkali metal silicate solution with hydrochloric or sulfuric acid in the presence of an electrolyte, controlling the ratio of the rate of adding chloride or sulfate ion in a silicaprecipitating step in which the pH of the reaction system is up to 10.0 to that in a neutralizing step of rendering the pH of the reaction system to 8.0 to 6.5 to at least 5 : 3, completing the neutralizing step within 30 minutes, and ripening for at least ten minutes. |