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:
Jul. 26, 1994
Filed:
Dec. 08, 1992
Takayuki Torii, Chiba, JP;
Takashi Haraoka, Chiba, JP;
Katsuhiro Nagayama, Chiba, JP;
Hitomi Hatano, Chiba, JP;
Noriyoshi Fukuda, Chiba, JP;
Yuichi Ishino, Kodaira, JP;
Takayuki Maruyama, Kodaira, JP;
Tasuku Saito, Kodaira, JP;
Kawasaki Steel Corporation, , JP;
Bridgestone Corporation, , JP;
Abstract
A method for producing a carbonaceous powder which can be used as dielectric fine particles to be dispersed in an insulating oil to produce an electrorheological fluid is provided. The method comprises the steps of subjecting a starting organic material selected from the group consisting of coal, coal tar, coal tar pitch, liquefied coal, coke, petroleum, petroleum tar, petroleum pitch, and resins to a heat treatment at a maximum temperature of 300.degree. to 800.degree. C. to produce carbonaceous material; pulverizing and classifying the material to produce carbonaceous particles having a mean particle size of 0.5 to 40 .mu.m and a maximum particle size of up to 50 .mu.m; and subjecting the particles to an additional treatment at an elevated temperature and/or a reduced pressure, said additional treatment being carried out at a temperature lower than said maximum temperature of the heat treatment. The resulting carbonaceous powder may optionally be subjected to a further pulverization treatment.