Abstract: A process for the preparation of precipitated silica is disclosed. The precipitated silica has a refractive index from about 1.440 to about 1.450, among other properties. The silica is prepared by a method including; a first step of using an initial feedstock of water, an electrolytic salt and a fraction of the total amount of silicate employed; a second step including preneutralizing the feedstock with the acidifying agent until about 50 to 85% of the amount of M2O present has been neutralized; a third step including introducing into the preneutralized feedstock the remaining fraction of alkali metal silicate in aqueous solution and the acidifying agent, under conditions such that the pH of the reaction medium remains substantially constant and from about 8.6 to about 9.

Abstract: The invention relates to precipitated silica microbeads having sensory properties in the mouth, and a specific surface CTAB of at least 100 m2/g, an oil uptake of at least 200 ml/g, a mean particle diameter from 50 &mgr;m to 600 &mgr;m, at the surface from 0.5 to 2 parts by weight, (expressed as zinc metal) of a zinc derivative with a degree of oxidation of 2 per 100 parts by weight of silica, a pH from about 7 to 9, and possibly between 0.2 and 5 parts by weight of a white pigment for 100 parts by weight of silica The invention also relates to a method for producing said microbeads by precipitation, treatment of the silica slurry with a soluble zinc compound, mechanical thinning of the cake resulting from the separation of the treated silica slurry, and drying by atomization. The invention further relates to their use in toothpaste preparations as sensory agents acting in the mouth.

Abstract: A method for preparing hollow particles comprising a dense silica shell, by precipitating active silica from an aqueous alkaline metal silicate on a core constituted in a material other than silica and by eliminating the material without destroying the silica shell. The particles are used as insulating materials; as hollow fillers for polymers, building materials, rubber, paper, paint; as absorbing agents; as toothpaste abrasives or additives; as support for the absorption and/or graining out active matter, the liberation of the active matter being effected by the destruction of the silica core by mechanical rupture or by dissolving the silica shell in a basic medium or by diffusion; as sun screening agents or sun screening agent supports or for the formulation of liquid matter in solid form.

Abstract: The invention discloses an abrasive precipitation silica useable in toothpaste compositions, said silica having a BET specific surface ranging from 15 to 300 m2/g, a DOP oil absorption ranging from 40 to 160 ml/g, a median particle diameter of at least 10 &mgr;m, generally ranging from 12 to 30 &mgr;m, a particle cohesion factor of at least 85% about for a median particle diameter ranging from 12 to 20 &mgr;m.

Abstract: The invention discloses a method for preparing particles comprising a dense silica shell and a core of another material, through rapid precipitation of active silica from a an aqueous alkaline metal silicate solution with pH adjustment by means of an acidifying agent, on a material support other than silica, separation of the silica slurry formed and drying of the recovered silica suspension. These composite particles consisting of a shell formed of dense silica and a non-polymer organic material core with biological, in particular phytosanitary, activity can be used for the slow release of the said solid non-polymer organic material with biological, in particular phytosanitary, activity, by slow diffusion through the silica shell.