Basf Aktiengesellschaft

Fasern Aktiengesellschaft

Basf Farben

Henning Wienand

Werner Ostertag

Helmut Knittel

Norbert Mronga

Egon Liedek

Christoph Schwidetzky

Harald Ochmann

Gunter Etzrodt

Ekkehard Schwab

Erwin Hahn

Bernhard Albert

Dietrich Lach

Paul Klingelhoefer

Hansulrich Reisacher

Peter Dimroth

Knut Bittler

Friedrich Closs

Roland Bauer

Hans-Ulrich Reisacher

Michael Nebel

Ferriferous bismuth vanadate pigments

A process for preparing transparent yellow iron oxide pigments by the precipitation of iron (II) hydroxide by adding an inorganic base to an iron (II) salt solution and subsequent oxidation to FeOOH.

Preparation of transparent yellow iron oxide pigments

In laked tris- or tetracationic polymethine dyes I ##STR1## the variables have the following meanings: A is the radical of a fused-on substituted or unsubstituted benzene or naphthalene nucleus,

Laked tris- or tetracationic polymethine dyes

An essentially monoclinic bismuth vanadate of the formula Bi[V.sub.1-x P.sub.x)O.sub.4 ] where x is from 0 to 0.1 has a chroma of .gtoreq.85, a lightness of .gtoreq.80, a hue angle of from 89 to 95 and a photochromism with a .DELTA.E value of .ltoreq.2 under the CIELAB system.

Bismuth phosphovanadate pigments

Thermostable bismuth vanadate/molybdate pigments are prepared by precipitating onto a pigment, obtained by calcination, of the formula

Thermostable bismuth vanadate/molybdate pigments

Magnetite pigments are prepared from iron(II) salt solutions by a process in which the mean particle size can be brought to a value within the range from 0.06 to 0.5 .mu.m by means of a residence stage between the precipitation stage and the oxidation stage.

Preparation of magnetite pigments: control of particle size

The invention relates to basic chromium aluminum sulfates which are soluble in cold water and are of the general formula

Basic chromium aluminum sulfates and their preparation

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.

Preparation of thermally stable lead chromate pigments

Yellow pigments containing bismuth vanadate and having the composition

Yellow pigment containing bismuth vanadate and having the composition

Growing community of inventors

Neulussheim, Germany

Henning Wienand