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:
Jun. 30, 1987
Filed:
Nov. 04, 1985
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
In the production of an .alpha.-iron oxide pigment by the hydrothermal treatment of a trivalent iron-containing solution or suspension, the improvement which comprises adding to the solution or suspension prior to the hydrothermal treatment active .alpha.-iron oxide seeds with lamellar or disc-like crystal form and a specific surface of at least 10 m.sup.2 /g, whereby the resulting pigment is lamellar with an Fe.sub.2 O.sub.3 content of at least 88%, an average particle diameter of from 0.5 to 20 .mu.m, an average ratio of diameter to thickness of from 20 to 100, and an almost normally distributed particle size distribution, the relative standard deviation of which, based on the average value of the normal distribution, is less than 0.3. The product has superior coloring properties and is used as a precursor compound for the production of lamellar magnetic pigments with superior magnetic properties.