Bayer Aktiengesellschaft

Franz Hund

Gunter Buxbaum

Peter Kresse

Ingo Pflugmacher

Peter Woditsch

Horst Brunn

Volker Hahnkamm

Gunter Linde

Wolfgang Rambold

Lutz Leitner

Peter Kiemle

Heribert Bade

Henning Erfurth

Wilhelm Holznagel

Willi Hennings

Bernd Stephan

Gerhard Schroeder

Ottfried Schlak

Jakob Rademachers

Gerhard Franz

Fritz Rodi

Johannes Niggemann

Gerhard Winter

Rolf Naumann

Heinrich-Christian Schopper

Peter Kohler

Friedrich Kindervater

Kurt Hill

Jacob Rademachers

Gerd Von Szadkowski

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

Synthetic, hexagonal, lamellar iron oxide particles, suitable as corrosion-inhibiting or decorative colored pigments, containing about 0.1 to 12% by weight of at least one oxide of an element of the IVth, Vth or VIth Main and Secondary Groups and of the IInd Secondary Group of the Periodic System of Elements.

Production of lamellar iron oxide pigments

In the preparation of highly orientatable needle-shaped ferrimagnetic iron oxide particles by the reduction and reoxidation of needle-shaped particles of hydrated oxide of iron which have been surface treated against sintering the improvement which comprises effecting the surface treatment by applying to the particles of hydrated oxide of iron one layer of oxygen-containing anions and a further layer of polyvalent cations, each layer weighing about 0.02 to 2% by weight of the particle. Advantageously, the polyvalent cation-containing layer is applied between two oxygen-containing anion layers, the oxygen-containing anions used are selected from the group consisting of silicate, phosphate, borate, vanadate, molybdate and tungstate, the polyvalent cations used are selected from the group consisting of aluminum, chromium, manganese, iron and gallium, each layer weighs about 0.1 to 1% of the weight of the particles and before the reduction and reoxidation the surface treated particles of hydrated oxide of iron are tempered at a temperature of about 600.degree. to 900.degree. C.

Coating iron oxide particles for magnetic recording

A process for increasing the color purity of iron oxide pigment particles admixed with color-modifying impurities and obtained by the Penniman process or the aniline process, comprising introducing the particles into a magnetic field, and removing from the magnetic field two fractions of different magnetizability, the first fraction being iron oxide pigment particles of increased color purity and the second fraction being enriched in impurities.

Magnetic separation to improve purity of iron oxide pigments

Readily dispersible finely divided solids such as pigments, coated with an organo-silicone polymer of the formula ##EQU1## wherein R.sup.I, R.sup.II, R.sup.III each independently is an optionally halogenated alkyl, alkenyl or aryl radical having from 1 to 10 carbon atoms;

Readily dispersible silicone-coated finely divided solids

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

A metal powder, suitable for magnetic recording, consisting essentially of iron, the individual particles being acicular and containing on average no more then 5 pores and consisting on average of no more than 2 metal cores is produced by precipitating and oxidizing an aqueous iron-(II)-salt solution to produce finely divided acicular iron-(III)-oxide-hydroxide, stabilizing it as by treatment with cadmium, lead, calcium, magnesium, zinc, aluminum, chromium, tungsten, a phosphorus oxide and/or a boron oxide, converting it into ferromagnetic iron oxide of low pore content, and reducing it to metallic iron with a gaseous reducing agent at about 300.degree. to 600.degree. C.

Ferromagnetic metal pigment essentially consisting of iron and a process

An anti-corrosion pigment comprising about 30.0 to 2.0 mole % of CaO and about 70.0 to 98.0 mole % of Me.sub.2 O.sub.3, wherein Me.sub.2 O.sub.3 is (1-x) Al.sub.2 O.sub.3 and x Fe.sub.2 O.sub.3, x is from 0 to 1 and up to about 25 mole % of the Fe.sub.2 O.sub.3 may be replaced by the corresponding quantity of Mn.sub.2 O.sub.3, and having a specific surface area according to BET of about 0.1 to 200 m.sup.2 /g and a percentage weight loss per gram of pigment, as determined by the Thompson corrosion test, of less than about 0.05% per gram of pigment is produced by calcining the corresponding metal oxides or materials which form the metal oxides on calcination at about 200.degree. to 1100.degree. C. The pigments are especially useful in making up anti-corrosion paints and lacquers.

Active anti-corrosion pigments based on calcium oxide, aluminium oxide

A finely divided magnetite pigment such as is used in magnetic tapes is stabilized against oxidation by contact with a heterocyclic nitrogen compound such as morpholine, triazole, piperazine or substitution products thereof. The heterocyclic compound can be applied as a solution or in vapor form.

Stabilization of magnetite pigments with heterocyclic nitrogen compounds

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.

Process for the production of iron oxide red pigments

An anti-corrosion pigment comprising about 30 to 70 mole % of an oxide of at least one metal selected from the group consisting of magnesium, calcium and zinc, about 70 to 30 mole % of Fe.sub.2 O.sub.3, and up to about 20 mole % of Cr.sub.2 O.sub.3, the pigment having a specific surface of about 1 to 30 m.sup.2 /g and exhibiting a weight loss of less than about 0.05% per gram of pigment by the Thomson corrosion test, is produced by calcining the corresponding metal oxides. The temperature is about 200.degree. to 650.degree. C. in the absence of chromium and about 200.degree. to 900.degree. C. when chromium is present.

Iron oxide-based anti-corrosion pigments

A pigment of high anti-corrosion properties comprises

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Krefeld, Germany

Franz Hund