Patents Assigned to BASF Farben
  • Preparation of thermally stable lead chromate pigments
    Patent number: 4530725
    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.
    Type: Grant
    Filed: June 28, 1984
    Date of Patent: July 23, 1985
    Assignees: BASF Farben, Fasern Aktiengesellschaft
    Inventors: Werner Ostertag, Peter Dimroth, Henning Wienand, Egon Liedek, Helmut Knittel, Gunter Etzrodt