Silica capable of being used in toothpaste compositions

Process for preparing silica by reacting an alkali metal M silicate, with an SiO2/M2O ratio of about 2 to 4, with an acidifying agent, optional maturation of the silica mash formed, separation and optional drying of the silica suspension recovered and optional grinding, wherein the operation for forming the silica mash is carried out according to the following steps:

• a first step comprises using an initial stock solution of water, an electrolytic salt from the group of:
• alkali metals, alkaline-earth metals, and an alkali metal M silicate;
• and optionally an acidobasic agent, at a temperature of about 70 to 98° C., the amount of electrolyte present being about 0.1 to 1 mol of alkali-metal electrolytic salt or of about 10 to 100 mmol of alkaline-earth-metal electrolytic salt per liter of stock solution or less than 10 g/l of alkali metal silicate, expressed as SiO2;
• a second step comprising introducing into said stock solution the alkali metal silicate as an aqueous solution and the acidifying agent, under conditions such that the pH of the reaction medium remains more or less constant and at a value of about 5.5 to less than 7, said reagents being introduced until the desired silica concentration is obtained in said medium, the reaction medium being maintained at a temperature of about 70 to 98° C.;
• and, after optional maturation, a third optional step comprising acidifying the reaction medium until a silica mash with a pH of less than 6 is obtained.