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:
Mar. 15, 1994
Filed:
Jul. 02, 1991
Hiroshi Oka, Hiroshima, JP;
Kazuaki Kouziro, Ube, JP;
Toshitada Shigemura, Ube, JP;
Tomohisa Moriya, Hiroshima, JP;
Katsumi Yamashita, Hiroshima, JP;
Kazushi Takama, Hiroshima, JP;
Takanobu Uemoto, Hiroshima, JP;
Kazuhiro Fujita, Hiroshima, JP;
Toda Kogyo Corp., Hiroshima, JP;
Abstract
Disclosed herein is a process for producing acicular magnetic iron oxide particles comprising the steps of: mixing an aqueous dispersion of acicular magnetic iron oxide particles with an aqueous solution of a Co salt and an alkaline aqueous solution, or an aqueous solution of a Co salt, an aqueous solution of an Fe(II) salt and and an alkaline aqueous solution; and heat-treating the alkaline suspension solution obtained at 50.degree. to 100.degree. C.; wherein an Sr salt, a Ba salt or an Sr salt and a Ba salt is added to one selected from the group consisting of said aqueous dispersion of acicular magnetic iron oxide particles, said aqueous solution of a Co salt, said aqueous solution of an Fe(II) salt, said alkaline aqueous solution and said alkaline suspension solution before heat-treatment, and at least one selected from the group consisting of Si compound, Al compound, Zn compound and Mg compound is added to one selected from the group consisting of said aqueous dispersion of acicular magnetic iron oxide particles, said aqueous solution of a Co salt, said aqueous solution of an Fe(II) salt, said alkaline aqueous solution, said alkaline suspension solution before heat-treatment and said alkaline suspension solution during heat-treatment.