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. 11, 1997
Filed:
Nov. 16, 1994
Hitoshi Maki, Tokyo, JP;
Shigeki Kato, Tokyo, JP;
Shinichi Azuma, Tokyo, JP;
Mikio Hayashi, Tokyo, JP;
Masatoshi Momose, Tokyo, JP;
Toyo Ink Manufacturing Co., Ltd., Tokyo, JP;
Abstract
A process for producing highly pure 6,13-dihydroquinacridone, which is a suitable intermediate for effectively producing a quinacridone pigment, for a short period of time at high yields, the process comprising providing a cylindrical reactor, providing an atmosphere free of oxygen in the cylindrical reactor, heating the cylindrical reactor so that the temperature of at least a surface of an inner wall of a cylinder of the cylindrical reactor is in the range of from 250.degree. to 400.degree. C., introducing a powder of 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester or a mixture of 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester with a liquid through a feed port provided in an upper portion of the cylindrical reactor, keeping the powder or the mixture in substantial contact with the inner wall of the cylindrical reactor so that an intramolecular alcohol-elimination reaction of the 2,5-di(arylamino)-3,6-dihydroterephthalic acid dialkyl ester takes place to form 6,13-dihydroquinacridone, and taking out the 6,13-dihydroquinacridone through an outlet provided in a lower portion of the cylindrical reactor.