| 摘要 |
A method for producing precipitated silicic acid products and silicates having a unique combination of physical and chemical properties is disclosed. The products are produced by acidulating a solution of an akali metal silicate with an acid until precipitation just begins. At this point the reaction mass is aged for a period of time and thereafter the acid addition is continued until the precipitated product is obtained. Products produced in accordance with the invention exhibit lower wet cake moisture (or higher percent solids) and are characterized by their low structure, low oil absorption, high abrasiveness and high pack density. The products can be used as abrasive and polishing agents in dentifrice compositions, in the production of molecular sieves, in paints and the like. In a particularly advantageous embodiment, an adduct material, such as aluminum, is added to control the refractive index of the precipitated silica. Products produced in this manner have particular utility for use as abrasion and gelling agents in clear toothpaste compositions.
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