Preparing an aqueous colloidal silica sol, useful to prepare silica, comprises mixing a water-soluble alkali metal silicate with an acidifying agent, followed by contacting with a basic anion exchange resin of hydroxyl type

• Main Authors: FUHRMANN, CLAUDIA, OEHM, DIETER, PAULAT, FLORIAN, PANZ, CHRISTIAN
• Format: Patent
• Language: English; German
• Published: 23.08.2012
• Subjects: CHEMICAL COMPOSITION OF GLASSES, GLAZES, OR VITREOUSENAMELS; CHEMISTRY; COMPOUNDS THEREOF; GLASS; INORGANIC CHEMISTRY; JOINING GLASS TO GLASS OR OTHER MATERIALS; METALLURGY; MINERAL OR SLAG WOOL; NON-METALLIC ELEMENTS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS,MINERALS OR SLAGS; SURFACE TREATMENT OF GLASS

Preparing an aqueous colloidal silica sol comprises (a) preparing an aqueous solution of a water-soluble alkali metal silicate by mixing the water-soluble alkali metal silicate or an aqueous alkali metal silicate solution with an acidifying agent; (b) contacting the acidic alkali metal silicate solution with e.g. a basic anion exchange resin of hydroxyl type; and (c) forming a stable colloidal silica sol by adjusting one/one of the nucleation and particle growth to appropriate temperature, concentration and pH value of the aqueous silica solution obtained from the step (b). Preparing an aqueous colloidal silica sol comprises (a) preparing an aqueous solution of a water-soluble alkali metal silicate with a pH of less than 2 by mixing the water-soluble alkali metal silicate or an aqueous alkali metal silicate solution with an acidifying agent; (b) contacting the acidic alkali metal silicate solution with a basic anion exchange resin of hydroxyl type and an acidic cation exchange resin of hydrogen type in an arbitrary order, where the anion exchange resin and cation exchange resin are spatial separated or mixed thoroughly; and (c) forming a stable colloidal silica sol by adjusting one/one of the nucleation and particle growth to appropriate temperature, concentration and pH value of the aqueous silica solution obtained from the step (b). Independent claims are included for: (1) the aqueous colloidal silica sol comprising = 5 ppm of aluminum, = 5 ppm of calcium, = 20 ppm of iron, = 5 ppm of barium, = 7 ppm of titanium, = 5 ppm of zirconium, = 5 ppm of magnesium and = 5 ppm of phosphorus, where the sum of the above impurities is less than 50 ppm; (2) the aqueous solution of silicic acid as an intermediate product obtained after the step (b) comprising the above impurities; and (3) silica obtained by the dehydration of the aqueous colloidal silica sol or aqueous silicic acid solution comprising the impurities. Die vorliegende Erfindung betrifft ein Verfahren zur Herstellung wässriger kolloidaler Silikasole hoher Reinheit aus Silikatlösungen, wässrige kolloidale Silikasole mit speziellem Verunreinigungsprofil sowie deren Verwendung. Ferner umfasst die Erfindung im Rahmen des Aufreinigungsprozesses als Zwischenprodukt anfallende hochreine wässrige Kieselsäure, durch Entwässerung erhältliches Siliziumdioxid hoher Reinheit und dessen Verwendung.