Bayer Aktiengesellschaft

Lanxess Deutschland Gmbh

Bayer Chemicals Ag

Horst Brunn

Franz Hund

Wilfried Burow

Peter Kresse

Gunter Buxbaum

Wolfgang Oehlert

Wolfgang Rambold

Helmut Printzen

Herbert Kunstmann

Klaus Nollen

Heribert Bade

Ulrich Meisen

Bernd Krockert

Holger Friedrich

Johannes Niggemann

Peter Kiemle

Carsten Rosenhahn

Jorg Krekel

Peter Kohler

Werner Fuhr

Gerd-Hermann Schulten

Berndt-Ullrich Kohler

Hans Sander

Axel Westerhaus

Willi Hennings

Karl-Heinz Van Bonn

Gerd Von Szadkowski

The present invention relates to zinc ferrite colour pigments, including a process for preparing and using them and, more particularly, the present invention relates to light-coloured zinc ferrite colour pigments having enhanced thermal stability, a magnesium content of from 0.01%-0.4% by weight, a color difference &#x394;E* according to DIN 53 772 at 260&#xb0; C. of &#x3c;3.0, a color difference &#x394;E* according to DIN 53 772 at 300&#xb0; C. of &#x3c;5.0, and a lightness of L*, measured in PE-HD full shade according to DIN 55 772 of &#x3e;52.5.

Heat-stable zinc ferrite colour pigments, process for preparing them and their use

The present invention relates to a process for preparing yellow iron oxide pigments by the precipitation method from iron(II) chloride or iron(II) sulphate raw material and calcium carbonate precipitant.

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The present invention relates to a process for the production of iron oxide brown, red and black pigments and to the use thereof.

Process for the thermal treatment of iron oxides in a circulating

The invention relates to clean color shade, yellow-tinged red iron oxide pigments, and a process for their manufacture, and their use.

Clean color shade, yellow-tinged red iron oxide pigments, and a process

Boron-containing iron-oxide pigments as disclosed which are prepared by a nitrobenzene reduction process. The boron is present in the pigments in a homogeneously doped form in amounts of 0.02 to 0.13% by weight, based on iron oxide. Preparation of the pigments is also described.

Boron-containing iron oxide pigments and a process for their preparation

Red iron oxide pigments with improved coloring properties wherein the isoelectric point of the pigments is greater than 7.

Red iron oxide pigments with improved coloring properties

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 black iron oxide pigments having a magnetite structure from iron ion-containing acidic waste water which comprises precipitating the iron ions with alkaline substances in a first stage at ambient temperature to produce a raw slurry and in a second stage, concentrating the raw slurry adjusted to a pH of from 5.0 to 8.0 with acidic substances and then ripening the concentrated slurry at temperatures above 70.degree. C.

Process for the production of black pigments based on iron

Iron oxide yellow pigments having a silking effect .DELTA.E.sub.1 *, less than or equal to 0.5, and having color values which range for L* from 52-63, for a* from 8 to 14 and for b* from 40 to 48 CIELAB units are produced by a process by first, forming needle-shaped .alpha.-FeOOH yellow pigment nuclei in the presence of compounds containing the elements B, Al, Ga, Si, Ge, Sn or Pb present in a quantity of from 0.05 to 10% by weight, where the quantity is calculated as the tri- or tetra-valent oxides of the compounds and based on the .alpha.-FeOOH which is precipitated during nucleation, and second, growing iron oxide yellow pigments on the thus formed iron oxide yellow nuclei.

Iron oxide yellow pigments having a low silking effect and a process for

A depot fertilizer composition comprising an inorganic matrix and another inorganic and/or organic component of the formula

Inorganic depot fertilizers

This invention relates to corrosion-inhibiting paints and lacquers containing pigments comprising an organic corrosion inhibitor intercalated into an inorganic matrix said pigment having the formula wherein ##EQU1## wherein Me(II)O is at least one divalent metal oxide;

Corrosion-inhibiting paints and lacquers

A zinc ferrite pigment comprising, by weight, about 99.8 to 90% of ZnFe.sub.2 O.sub.4 and about 0.2 to 10% of the component system (1-x)Al.sub.2 O.sub.3 and xP.sub.2 O.sub.5 wherein 0&lt;x&lt;1 is produced by calcining a suitable mixture of compounds. The resulting pigments are of high color quality and are substantially halogen-free, rendering them especially useful industrially even as anti-corrosion pigments.

Halogen-free zinc ferrite yellow pigments containing alumina and

In the production of needle-shaped magnetic iron oxide pigments by treating iron with a nitro-aromatic in the presence of .alpha.-FeOOH nuclei to form .alpha.-FeOOH particles and an amino-aromatic, and thereafter dehydrating the .alpha.-FeOOH particles and reducing them, the improvement which comprises forming the .alpha.-FeOOH nuclei at about 0.degree. to 90.degree. C. in a suspension of metallic iron, an iron-(II)-salt and a nitro-aromatic by adding a basic precipitant in about 10 to 95% of the amount required for the complete precipitation of the iron in the iron-(II)-salt. Advantageously the metallic iron comprises cast iron, the nitro-aromatic comprises nitrobenzene, the amino-aromatic comprises aniline, the basic precipitant comprises at least one of ammonia and a basically reacting alkali metal, alkaline earth metal or ammonium salt, the nuclei formation is carried out at about 10.degree. to 60.degree. C., and the basic precipitant is added in about 20 to 80% of the amount required for the complete precipitation of the iron in the iron-(II)-salt, additional iron and nitrobenzene being added to the suspension of precipitated nuclei to form the .alpha.-FeOOH particles.

Production of magnetic iron oxides

In the production of an iron oxide red pigment by reducing nitrobenzene with metallic iron in the presence of an acidic iron (II) salt solution, separating off the iron oxide pigment obtained from the reaction medium by washing out, and calcining the pigment at a temperature in the range of about 600.degree. to 1100.degree. C., the improvement which comprises adding an aluminum salt solution over a period of about 5 to 360 minutes at a temperature of about 20.degree. to 100.degree. C. to the iron oxide suspension accumulating during reduction of the nitrobenzene, the suspension containing about 150 to 600 g of iron/l and a residual iron (II) chloride content of about 20 to 160 g/l expressed as iron, the initial pH-value of the iron oxide suspension of about 3 to 5 being adjusted over a period of about 5 to 180 minutes to a final pH-value of about 5.5 to 6.5.

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Meerbusch, Germany

Horst Brunn