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:
Sep. 12, 1995
Filed:
Dec. 23, 1994
Yoshio Fukui, Yokkaichi, JP;
Tatsuto Yoshioka, Yokkaichi, JP;
Chikara Sugimoto, Yokkaichi, JP;
Manabu Okuyama, Yokkaichi, JP;
Norioki Mine, Yokkaichi, JP;
Masahiko Yamagishi, Yokkaichi, JP;
Mitsubishi Chemical Corporation, Tokyo, JP;
Abstract
The present invention provides a method of preparing high purity 2,6-naphthalene dicarboxylic acid in which the contents of coloring substances, heavy metal and bromine compounds can be reduced by dissolving coarse crystals of 2,6-naphthalene dicarboxylic acid containing impurities in supercritical or subcritical water containing an entrainer composed of an organic solvent containing oxygen and having a specific solubility parameter, and by cooling an obtained solution to cause crystals to precipitate so as to separate the crystals from mother liquor.