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:
Apr. 05, 1983
Filed:
Nov. 18, 1981
Yasuo Araki, Kawachinagano, JP;
Hajime Uno, Sakai, JP;
Shigeharu Higuchi, Sakai, JP;
Seiji Matsumoto, Sakai, JP;
Sakai Chemical Industry Co., Ltd., Osaka, JP;
Abstract
A method of producing cobalt-modified magnetic particles is provided. The method comprises heating an aqueous suspension of ferric hydroxide at temperatures of 100.degree.-250.degree. C. at an alkaline pH in the presence of a water soluble organic or inorganic compound capable of forming complexes with iron as a growth regulating agent, and preferably also in the presence of .alpha.-ferric oxide seed crystals of minor axes not larger than 0.4 microns in average in amounts of 0.1-25 mole % in terms of the Fe content thereof in relation to the ferric hydroxide, converting the obtained .alpha.-ferric oxide into .gamma.-ferric oxide by reduction thereof followed by oxidation, maintaining an aqueous suspension of the .gamma.-ferric oxide at temperatures of 30.degree.-50.degree. C. at an alkaline pH in the presence of ferrous hydroxide and cobaltous hydroxide in amounts of 0.5-50 mole %, respectively, in relation to the Fe content of the .gamma.-ferric oxide in the suspension for a length of time sufficient to modify the .gamma.-ferric oxide particles.