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, 1994
Filed:
Apr. 13, 1993
Toshihiko Furukawa, Kitakyushu, JP;
Katsuhiko Sakura, Kitakyushu, JP;
Kiyoshi Hashimoto, Kitakyushu, JP;
Nobuaki Egashira, Kitakyushu, JP;
Nobuo Moriya, Yokohama, JP;
Sachio Asaoka, Yokohama, JP;
Nobuyuki Suda, Yokohama, JP;
Susumu Yamamoto, Yokohama, JP;
Nippon Steel Chemical Co., Ltd., Tokyo, JP;
Chiyoda Corp., Yokohama, JP;
Abstract
This invention relates to a process for preparing bisphenol A of good heat stability by heat-treating bisphenol A containing a very small amount of impurities in a molten state at 185.degree. to 220.degree. C. for 5 to 60 minutes in an oxygen-free atmosphere and the process yields bisphenol A of good heat stability which shows reduced coloration when heated. Bisphenol A prepared by this process has excellent properties relating to color and is particularly suitable as raw material for the manufacture of polycarbonates where the requirement for color is strict.