Bayer Aktiengesellschaft

Bernd Krockert

Gunter Linde

Gunter Buxbaum

Helmut Printzen

Horst Brunn

Manfred Eitel

Peter Kuske

Hans-Ulrich Hofs

Hans-Peter Biermann

Karl-Werner Ganter

Klaus Rohbock

Axel Westerhaus

Kurt Schafer

Karl-Heinz Van Bonn

The invention relates to a process for jet grinding inorganic pigments comprising the steps of compacting the inorganic pigments on a roller compactor at a predetermined linear force, and jet grinding the compacted inorganic pigments.

Process for the jet milling of inorganic pigments

A method for coloring building materials is disclosed, wherein a pigment suspension is added to the building materials. The pigment suspension based on pigment granules contains at least one pigment such as iron oxide, and a soluble phosphate salt. The soluble phosphate salt has a number ratio of monofunctional metal ions to phosphorus of 2:1 to 1:1, and is exemplified by sodium pyrophosphate, sodium polyphosphate, and sodium hexametaphosphate.

Process for coloring building materials

Process for the preparation of a pigment suspension

Building materials are colored with pigments, for example iron oxide pigments, in the form of granules produced from a suspension of one or more pigments wherein the suspension also contains 0.05 to 5% of soluble salts, based on pigment weight.

Building materials such as plaster, lime-sand bricks, fiber cement parts, cast stones, roof tiles, flagstone and paving setts are colored by incorporating therein in organic granules produced from a suspension of one or more inorganic pigmenting agents and a hydrolyzed or poorly soluble compound of one or more ion types present per se as an essential constitutent in one or more pigments.

Colored building materials are produced by incorporating into the building materials inorganic pigments in the form of granulates which are free-flowing and not dust forming wherein the pigments are produced from spray dried granulates by after-granulating.

Low-silking iron oxide yellow pigments having improved color qualities are produced by a novel method which utilizes both precipitation process and the Penniman process. Pigments are nucleated and grown by precipitation to achieve multiplication factor of 2.5 to 7 and additional pigment growth is carried out by the Penniman process.

Process for the production of iron oxide yellow pigments

An improved process is disclosed for preparing iron yellow pigments from iron--(II) salt solutions, in the presence of iron scrap, by injection of air at elevated temperatures. After formation of the pigment, the reaction suspension is stirred without additional gas injection, whereby lighter, purer yellow pigments are obtained.

Process for the preparation of iron yellow pigments

A pigment useful for coloring building materials such as bricks is a heat-stable isometric iron oxide brown pigment of .gamma.-Fe.sub.2 O.sub.3 structure which has a silicon content, expresed as SiO.sub.2, of 0.1 to 12% and an Al content, expressed as Al.sub.2 O.sub.3, of 0.02 to 5%.

Heat stable iron oxide pigments of upsilon-Fe.sub.2 O.sub.3 structure, a

A process for the production of iron oxide yellow pigments by the Penniman-Zoph process from the raw materials iron (II) sulfate, sodium hydroxide and metallic iron, is disclosed in which iron (II) is oxidized to iron (III) by gassing with air in the presence of goethite nuclei, the iron (III) sulfate is dissolved to form iron (II) and the goethite nuclei are built up to iron oxide yellow pigments, characterized in that the gassing with air and dissolving of the metal are carried out in separate vessels.

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Wesel, Germany

Bernd Krockert