Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2005-03-21
2010-06-08
Seidleck, James (Department: 1796)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S308100, C528S308300
Reexamination Certificate
active
07732556
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.
REFERENCES:
patent: 6380345 (2002-04-01), Uenishi et al.
patent: 2002/0161166 (2002-10-01), Nakane et al.
patent: 57-135828 (1982-08-01), None
patent: 5-214089 (1993-08-01), None
Korting Website Steam Jet Vacuum Injectors; www. koerting.de/products/vacuum—technology/steam—jet—vacuum—ejectors/.
Akahane Yoshio
Hamano Toshiyuki
Okubo Kazuyuki
Yamamoto Masanori
Listvoyb Gregory
Mitsubishi Chemical Corporation
Oblon, Spivak McClelland, Maier & Neustadt, L.L.P.
Seidleck James
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