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:
Dec. 06, 1994
Filed:
Apr. 18, 1994
Sachio Asaoka, Yokohama, JP;
Tetsuo Maejima, Tokyo, JP;
Kouji Sakashita, Tokyo, JP;
Noriyuki Yoneda, Tokyo, JP;
Makoto Yasui, Yokohama, JP;
Nobuhiro Onda, Tokyo, JP;
Tsuneo Watanabe, Kawasaki, JP;
Nobuo Moriya, Yokohama, JP;
Akio Shindo, Yokohama, JP;
Hiroaki Nishijima, Ebina, JP;
Athumi Kukudome, Yokohama, JP;
Ryuichi Inaba, Sagamihara, JP;
Takashi Imazeki, Ichikawa, JP;
Karou Shimogawara, Fujisawa, JP;
Chiyoda Corporation, Yokohama, JP;
Abstract
High quality bisphenol A is produced from a neutral crystalline adduct of bisphenol A and phenol by fusing the adduct in an atmosphere having a maximum oxygen content of 0.005% by volume, followed by evaporation of liberated phenol. The crystalline adduct may be mixed with an aliphatic carboxylic acid before the fusion to reduce the coloring of the product. When an acidic crystalline adduct is used, the use of a strong alkali salt of an aliphatic carboxylic acid is suitably used. Interior surfaces of the apparatuses for carrying out the fusion and evaporation are desirably washed with an organic solvent to remove oxygen therefrom. The evaporation of phenol is suitably performed by two stage steam stripping wherein a used stripping gas obtained in the second stage is employed as a stripping gas in the first stage while steam is used as the stripping gas in the second stage.