Preparation of thermally stable lead chromate pigments
AssigneesBASF Farben, Fasern Aktiengesellschaft
InventorsWerner Ostertag, Peter Dimroth, Henning Wienand, Egon Liedek, Helmut Knittel, Gunter Etzrodt
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Abstract
Thermally stable lead chromate pigments or pigments containing lead chromate, which have high color strength and are provided with a precipitated coating containing silicon dioxide, are prepared by a process in which an aqueous pigment suspension is mixed once or several times with an aqueous MgSiF.sub.6 solution, the pH being maintained at 4.5-9.5 and the temperature at 50.degree.-95.degree. C., and the pigment is then separated off and worked up, these steps being carried out in a conventional manner.
Claims3
A process for the preparation of a thermally stable lead chromate pigment, or pigment containing lead chromate, which has a high color strength and is provided with a precipitated coating containing siliccon dioxide, wherein an aqueous pigment suspension is mixed with an aqueous MgSiF.sub.6 solution, the pH being maintained at 4.5-9.5 and the temperature at 50.degree.-95.degree. C. and the pigment is then separated off and worked up, these steps being carried out in a conventional manner.
Dependencies are inferred from the claim text.