| 摘要 |
The invention discloses an abrasive precipitation silica useable in toothpaste compositions, said silica having a BET specific surface ranging from 15 to 300 m<2>/g, a DOP oil absorption ranging from 40 to 160 ml/g, a median particle diameter of at least 10 mu m, generally ranging from 12 to 30 mu m, a particle cohesion factor of at least 85 % about for a median particle diameter ranging from 12 to 20 mu m. Method for preparing silica by reacting an alkaline metal silicate with an acidifying agent, to form a silica slurry, separating and optionally drying the recuperated silica suspension, the operation for forming the slurry being effected according to the following steps: a first step consisting in using one initial heel solution constituted of water, an electrolyte salt of the alkaline or alkaline-earth metal group and optionally of one acidobasic agent; a second step consisting in introducing the silicate and the acidifying agent, the reaction medium pH remaining constant from 4 to 7 and particularly from 5.8 to 6.7; and a third optional step, consisting in acidifying the reaction medium until a silica slurry with a pH of less than 6 and particularly of 4 is obtained. The silica is useful in toothpaste compositions. Toothpaste compositions containing the said silica are also disclosed.
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