Abstract: The present invention relates to pure-coloured, readily dispersible iron oxide red pigments having high grinding stability, to a process for preparing them, and to their use.

Abstract: The present invention relates to pure-coloured, readily dispersible iron oxide red pigments having high grinding stability, to a process for preparing them, and to their use.

Abstract: Pure-coloured iron oxide yellow pigments having a silking index of less than 5 and a heat resistance of greater than 220.degree. C. in polyethylene for at least 5 minutes are obtained by oxidation of metallic iron with nitrobenzene in an acid medium in the presence of compounds of elements chosen from main groups 3 and 4 of the periodic table.

Abstract: The invention relates to the use of synthetic (synthetically produced) iron raw materials to prepare iron oxide pigments in the Penniman process and other iron-dissolution processes.

Abstract: A reactor for corrosive and abrasive reaction mixtures having an upper setion and a conically tapered lower reaction section, with a screw mixer consisting of a jacketed band surrounding a conveyor screw, suspended fron the top of the reactor, and an inlet for solid reactants which leads directly into the vertical conveying device.

Abstract: The invention relates to the use of synthetic (synthetically produced) iron raw materials to prepare iron oxide pigments in the Penniman process and other iron-dissolution processes.

Abstract: The invention relates to the use of synthetically produced, bainite-rich iron raw materials to prepare iron oxide pigments.

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

Abstract: Isometric iron oxide pigments are prepared by an improved process by precipitation of aqueous solutions containing iron (II) salts with alkaline precipitating agents followed by oxidation of the precipitate at temperatures of from 20.degree. C. to 100.degree. C., wherein the improvement comprises adjusting the iron (III) content to 1 to 25 mol %, based on the total iron, before precipitation.

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

Abstract: Red iron oxide pigments having a lower metal impurity content and enhanced purity of color are disclosed as being comprised of clusters of spherical particles.

Abstract: An inorganic pigment comprising a content of at least 0.1% by weight and at most 5% by weight of one or more polyorganosiloxanes, wherein the polyorganosiloxanes have viscosities of 10 to 100,000 mPa.s and a relative molecular weight of 500 to 500,000, have no reactive or crosslinking groups, contain at least one C.sub.9 -C.sub.25 Si-alkyl and/or one C.sub.9 -C.sub.25 Si-aryl group per molecule, the total content of these groups in the polyorganosiloxane being 7-70% by weight and the other organic radicals contained in the polyorganosiloxane having 1 to 8 carbon atoms. Such pigments can be used in lacquers, emulsion paints, plastics, toners, magnetic recording materials, building materials and enamels.

Abstract: A process is disclosed for preparing iron oxide black pigments obtained by the nitrobenzene reduction process, wherein the iron oxide black is heated to 400.degree.-800.degree. C. in a slightly oxidizing atmosphere with optional milling. The pigments are useful for coloring plastics, coatings and building materials.

Abstract: Thermostable pigments for coloring stoving lacquers, coil coat lacquers, plastics, sand granulates, lime sandstone, enamel or ceramic glazes are zinc ferrite color pigments containing from 0.01 to 0.5% by weight of lithium.

Abstract: Isometric oxidation resistant and heat resistant iron oxide black pigments having a foreign metal content of less than 5 ppm of each of As, Pb and Ba, less than 200 ppm total of Ca, BaSO.sub.4, Zn, Sb and Cr and from 0.05 to 2% by weight, calculated as trivalent or tetra-valent oxides, of B, Al, Ga, Si, Ge and Sn, are useful in coloring lacquers, thermoplastic synthetic resins and building materials as well as for low coercivity iron oxide black pigments in magnetic toners.

Abstract: Iron oxide red pigments comprise clusters of a plurality of pigment particles, preferably at least five intergrown spherical particles, are prepared by conducting nuclear formation of iron oxide yellow .alpha.-FeOOH in the presence of compounds of the elements, B, Al, Ga, Si, Ge, Sn or mixtures thereof in quantities of from 0.05 to 10% by weight, calculated as tri- or tetravalent oxides and based on the arithmetically calculated precipitated .alpha.-FeOOH nuclei, separating brine from the resulting yellow slurry to isolate an iron oxide yellow paste, drying and annealing the paste to form iron oxide red pigment and grinding the red pigment, which pigment is useful in coloring foodstuffs, lacquers, plastics and building materials.

Abstract: A bright, color-pure iron oxide red pigment is produced by an improved process by precipitation of iron(II) salts in aqueous solution with an alkaline precipitating agent, oxidation at temperatures of from 20.degree. C. to 100.degree. C. and annealing of the resulting precipitation products under air to form iron oxide red pigments, wherein the improvement comprises before adding the alkaline precipitating agent, the iron(III) content of the aqueous solution is adjusted to 1 to 15 mol %, based on the total iron content of the iron salt solution.

Abstract: Heat resistant iron oxide yellow pigments containing aluminium compounds of the formular (AlO).sub.x PO.sub.4 (OH).sub.x-3 where x is a value from 3 to 10 is prepared by applying the aluminum compund to an iron oxide pigment and is useful as a coloring agent in lacquers and synthetic thermoplastic materials.

Abstract: 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.

Abstract: 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.