(54) Title: SOLID PARTICLES HAVING A SILICATE COATING (54) Bezeichnung : FESTKoRPERPARTKEL MIT SILKATBESCHICHTUNG (57) Abstract: The invention relates to a method for producing solid particles having a silica coating, comprising the following steps: dispersing the solid particles to be coated in an agueous medium to produce a solid particle dispersion, adjusting the pH of the solid particle dispersion by means of a buffer system to produce a buffered solid particle dispersion, and adding an alkaline silicate solution to the buffered solid particle dispersion to form the silica coating on the solid particles during a coating period, wherein the amounts of buffer system and alkaline silicate solution are selected such that the pH of the buffered solid particle dispersion before the addition of the alkaline silicate solution is at least 7.0 and after completion of the addition of the alkaline silicate solution is at most 11.0. The solid particles are preferably inorganic solids, especiall

摘要

The invention relates to a method for producing solid particles having a silica coating, comprising the following steps: dispersing the solid particles to be coated in an agueous medium to produce a solid particle dispersion, adjusting the pH of the solid particle dispersion by means of a buffer system to produce a buffered solid particle dispersion, and adding an alkaline silicate solution to the buffered solid particle dispersion to form the silica coating on the solid particles during a coating period, wherein the amounts of buffer system and alkaline silicate solution are selected such that the pH of the buffered solid particle dispersion before the addition of the alkaline silicate solution is at least 7.0 and after completion of the addition of the alkaline silicate solution is at most 11.0. The solid particles are preferably inorganic solids, especially acid-labile solids. The method is especially preferably used for silica coating of acid-labile feature substances for security features, security papers and value documents.