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:
Jun. 08, 2010
Filed:
Mar. 21, 2005
Kazuyuki Okubo, Mie, JP;
Masanori Yamamoto, Mie, JP;
Yoshio Akahane, Mie, JP;
Toshiyuki Hamano, Mie, JP;
Kazuyuki Okubo, Mie, JP;
Masanori Yamamoto, Mie, JP;
Yoshio Akahane, Mie, JP;
Toshiyuki Hamano, Mie, JP;
Mitsubishi Chemical Corporation, Tokyo, JP;
Abstract
A problem of the invention is to provide a process of producing polyesters having a stable quality and a process of producing polyesters with a greatly reduced load against the environment. The invention relates to a process of producing polyesters by using a polycondensation reaction apparatus provided with one or more sets of an ejector, a condenser placed in the downstream portion of the ejector and a hot well tank connected to the condenser via a barometric leg and including a step of driving the ejector by a vapor composed mainly of 1,4-butanediol, condensing the vapor composed mainly of 1,4-butanediol as discharged from the ejector in the condenser placed in the downstream portion of the ejector, and making the reactor in a reduced pressure state to undergo polycondensation reaction, characterized in that the concentration of tetrahydrofuran contained in a sealing liquid in at least one hot well tank is not more than 4% by weight.