Magnetic iron oxides with improved orientability and a process for their production
AssigneeBayer Aktiengesellschaft
InventorsPeter Woditsch, Gunter Buxbaum, Franz Hund, Volker Hahnkamm
Life of this patent
Estimating the term…
Abstract
An acicular, magnetic iron oxide pigment containing about 0.1 to 2 percent by weight of zinc and phosphate ions is produced by growing seeds and subsequently reducing and optionally reoxidizing acicular FeOOH. Said seeds were formed by precipitation from an iron (II) salt solution in the presence of about 0.1 to 4 percent by weight of zinc ions and about 0.1 to 2 percent by weight of phosphate ions based on the formed seeds.
Claims7
An acicular, magnetic iron oxide pigment containing about 0.1 to 2 percent by weight of zinc and phosphate ions.
In the production of an acicular, magnetic iron oxide pigment by adding a basically reacting precipitant to an iron (II) salt solution to precipitate iron hydroxide, carbonate or a basic iron salt, followed by oxidation at a pH of about 2 to 8 to form FeOOH seeds, growing said seeds and subsequently dehydrating and reducing, the improvement which comprises carrying out seed formation in the presence of about 0.1 to 4 percent by weight of zinc ions and about 0.1 to 2 percent by weight of phosphate ions, based on the .alpha.-FeOOH to be precipitated.
Dependencies are inferred from the claim text.