The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 13, 2003
Filed:
Aug. 31, 2001
Applicant:
Inventor:
Ulrich Meisen, Kall, DE;
Assignee:
Bayer Aktiengesellschaft, Leverkusen, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G03G 9/083 ; C01G 4/908 ;
U.S. Cl.
CPC ...
G03G 9/083 ; C01G 4/908 ;
Abstract
This invention relates to magnetite particles with a mean particle size of 0.1 to 0.3 &mgr;m, a specific surface area of 6 to 9 m /g, a coercive force of 80 to 110 Oe, a residual magnetization of 13 to 20 nTm /g, a pH of 7 to 10 and a bulk density of 0.6 to 0.9 g/cm , by heating an aqueous solution of an alkaline component under inert gas, to a precipitation temperature of 65-85° C., adding iron (II) and iron (III) components and oxidizing the suspension with an oxidizing agent at a speed of 7-25 mol % Fe (II)/h.