SOLID PARTICLES HAVING SILICATE COATING Russian patent published in 2015 - IPC C09C3/06 C09K11/02 

FIELD: chemistry.

SUBSTANCE: invention is related to a method for producing solid particles having a silica coating, which are suitable to increase the falsification security of documents of value. Silica-coated solid particles are produced by dispersing solid particles in an aqueous medium to produce a solid-particle dispersion, and setting the pH value of the solid-particle dispersion by a buffer system, or by dispersing the solid particles in the buffer solution of a set pH value, producing a buffered solid-particle dispersion. A basic silicate solution added to the buffered solid-particle dispersion. The silica-coated solid particles are separated from the buffered solid-particle dispersion, dried and annealed. The pH value before addition of the basic silicate solution, is at least 8.0, and after the addition is at most 11.0. The buffer system is selected from the group consisting of potassium hydrogen carbonate/potassium carbonate, sodium hydrogen carbonate/sodium carbonate, and mixtures thereof. The solid particles are inorganic solids, preferably acid-labile solids.

EFFECT: proposed method provides protection of inorganic solids, in particular, acid-labile feature substances used in documents of value, against environmental influences and action of acids.

18 cl, 6 dwg, 1 ex