Bayer Aktiengesellschaft

Klaus Kohler

Peter Woditsch

Eckhard Bayer

Klaus Nollen

Heribert Stutgens

Hans Sander

Fritz Rodi

Karl-Heinz Schultz

Hilmar Rieck

An inorganically after-treated TiO.sub.2 pigment with a coating of hydrophobicizing and hydrophilicizing organic substances, which pigment comprises more than about 95% by weight of TiO.sub.2, shows a loss on annealing of less than about 0.8% (after subtraction of the carbon content) and has a grindometer value smaller than about 30, corresponding to a value of more than about 5.6 on the Hegman scale, is produced by micronizing a mixture of an inorganically after-treated TiO.sub.2 pigment, an untreated TiO.sub.2 pigment and hydrophobicizing and hydrophilicizing organic substances, the after-treated pigment being employed in about 1 to 40% by weight of total TiO.sub.2 pigment and the hydrophobicing and hydrophilicizing substances being employed in about 0.3 to 5% by weight of TiO.sub.2 pigment. The pigments are readily dispersible which simplifies their use in pigmenting lacquers, plastics and paper.

Readily dispersible TiO.sub.2 pigment

An inorganic pigment exhibiting improved gloss and distribution in lacquer binders, carrying a coating comprising a polyhydrogen siloxane and an alkanolamine. Advantageously the alkanolamine comprises at least one of triethanolamine, triisopropanolamine, diethanolamine, diisopropanolamine and 2-amino-2-methyl-propanol-1, the polyhydrogen siloxane is a polymethylhydrogen siloxane having more than 5 Si atoms, and the pigment comprises TiO.sub.2 or a titanate carrying an inorganic coating, the polyhydrogen siloxane plus alkanolamine ranging from about 0.3 to 1% by weight of the pigment and the ratio by weight of the polyhydrogen siloxane to alkanolamine ranging from about 1:2 to 1:5.

Inorganic pigments with improved gloss and distribution in lacquer

An inorganic pigment exhibiting improved gloss and distribution in lacquer binders, carrying a coating comprising a SiOH-containing organosilicon compound and an alkanolamine. Advantageously the alkanolamine comprises at least one of triethanolamine, triisopropanolamine, diethanolamine, diisopropanolamine and 2-amino-2-methyl-propanol-1, the organosilicon compound is of the formula ##STR1## wherein n&gt;3, R and R.sup.1 each independently is alkyl, cycloalkyl, aryl, alkenyl or a group of the formula ##STR2## wherein m&gt;1, the organosilicon compound having an OH:Si ratio within the range of about 1:1 to 1:20, and the pigment comprises TiO.sub.2 or a titanate carrying an inorganic coating, the organosilicon compound plus alkanolamine ranging from about 0.3 to 1% by weight of the organosilicon compound to alkanolamine ranging from about 1:2 to 1:5.

Inorganic pigments with improved gloss and good distribution in lacquer

A metallic iron-containing starting material such as iron filings, iron powder or a reduced ore such as ilmenite is oxidized with air in the presence of 5 to 40% of iron oxide and/or iron oxide hydroxide nuclei and about 2.5 to 200% of an electrolyte, percentages being based on metallic iron by weight. The oxidation is effected in aqueous suspension at 75.degree. to 100.degree. C and a pH of 4 to 6.5. If the nuclei are magnetite-free, at least the first quarter of the oxidation should be at pH 5 to 6.5. Preferred electrolytes are transition metal salts. The pigments are more intense in color and have a more pronounced blue tinge.

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Krefeld, Germany

Klaus Kohler