Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-06-02
2001-06-26
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06252034
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a polycarbonate resin and, specifically, to a process for producing a polycarbonate resin through a melt polycondensation reaction between an aromatic diol compound and a carbonic acid diester. More specifically, the present invention relates to improvements on a valve, gear pump, flange or flow passage for the transfer of a reaction mixture among a plurality of polymerization reactors in an industrial process for producing a polycarbonate resin through a melt polycondensation reaction. The improvements in the present invention are applied to the discharge of a polycarbonate resin from a final polymerization reactor and the transfer of the polycarbonate resin to the following step.
2. Prior Art
An aromatic polycarbonate resin is widely used as a molding material because it is excellent in mechanical properties such as impact resistance as well as heat resistance and transparency. Known processes for producing such an aromatic polycarbonate resin include one (interfacial process) in which an aromatic diol compound such as bisphenol and phosgene are directly reacted with each other and one (melting process) in which an aromatic diol compound such as bisphenol and an aromatic carbonic acid diester such as diphenyl carbonate are subjected to an ester exchange reaction.
Out of these production processes, the process for producing a polycarbonate through an ester exchange reaction between an aromatic diol compound and an aromatic carbonic acid diester is generally carried out by distilling off from a reaction mixture a monohydroxy compound such as a phenol by-produced by gradually elevating the reaction temperature from 150° C. which is the lowest temperature required to start an ester exchange reaction to about 350° C. in the presence of an organic acid salt, inorganic acid salt, oxide, hydroxide, hydride or alcoholate of a metal as a catalyst and gradually reducing the pressure from atmospheric pressure to 13.3×10
−6
MPa.
In the step of transferring the reaction mixture between polymerization reactors and the step of discharging the reaction mixture from the final polymerization reactor, valves, pumps, flanges and flow passages (pipes) are used. These transfer members are used at a high temperature and a high degree of vacuum. Since the viscosity of the reaction mixture rises to an extremely high level, generally 200 to 10,000 Pa·S (2,000 to 100,000 poise), which differs according to reaction conditions, along with the proceeding of the reaction (reaching completion), the pressure of the pump must be increased in accordance with resistance (pressure loss) generated in the pipe (flow passage) to transfer the reaction mixture through the pipe, and these transfer members must stand high pressure.
The term “reaction mixture” as used herein means a mixture obtained after a polycondensation reaction starts, proceeds or ends in the step of obtaining an aromatic polycarbonate by carrying out the melt polycondensation reaction of a mixture containing an aromatic diol compound and an aromatic carbonic acid diester as essential ingredients in the presence of an ester exchange catalyst. A reaction mixture whose polymerization degree proceeds to some extent is generally called “prepolymer” according to chemical terminology and a reaction mixture whose polymerization degree proceeds further is called “polymer” according to chemical terminology.
REFERENCES:
patent: 5516878 (1996-05-01), Sasaki et al.
patent: 7-268091 (1995-10-01), None
Sasaki Katsushi
Sawaki Toru
Shimonaru Masashi
Uenishi Kazuhiro
Boykin Terressa M.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teljin Limited
LandOfFree
Process for producing a polycarbonate resin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing a polycarbonate resin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing a polycarbonate resin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2455185