Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2002-02-26
2004-06-22
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C422S135000, C528S198000
Reexamination Certificate
active
06753403
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process and an apparatus for producing polycarbonate, which is suitable for producing polycarbonate from diphenyl carbonate and an alcohol such as bisphenol A, etc. as raw materials by transesterification upon mixing with a reaction catalyst and additives such as a color adjustment, etc.
BACKGROUND ART
In a process using vertical agitation reactors as disclosed in “Polycarbonate Resin”, page 66, published by Nikkan Kogyo Shinbun, a larger number of agitation reactors are required for continuous production with increasing scale of the facility, rendering the process uneconomical.
From the viewpoint of a model for perfect mixing vessels ganged together in series as an economical apparatus structure, it is effective to use horizontal agitation reactors capable of providing a large number of such perfect mixing vessels.
A spectacle rim-formed polymerization apparatus as disclosed in FIG. 2.49(b), Cl-43, C•Engineering section, of Mechanical Engineering Handbook, is a continuous agitation reactor, which can provide ideal extrusion flow characteristics, that is, a large number of perfect mixing vessels as ganged together in series, but the highly viscous liquid, when treated therein, tends to attach to the surface of the agitator center shaft and reside thereon with increasing liquid viscosity. That is, no sharp residence time distribution function curve can be obtained. Its mode is shown by a delta response curve in
FIG. 8
, which is based on test data on relations between the number of model vessels for perfect mixing vessels as ganged together in series and the residence time distribution function. In the spectacle rim-formed polymerization apparatus, deviation from the theoretical curve occurs around the point where the dimensionless number of time, t/to, exceeds 1.3. This means that a portion of the liquid resides in the dead zone of agitation, resulting in a problem of polymer quality deterioration.
In
FIG. 8
, “n” is the number of theoretical plates corresponding to perfected mixing vessels. The actual number of Brade partition plates is four stages. And the viscosity is 5 kPa·s.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a process and an apparatus for producing polycarbonate, which can improve the quality of polycarbonate as a polymerization product polymer.
Another object of the present invention is to provide a process and an apparatus for producing polycarbonate, designed to reduce the investment and operating costs.
According to one aspect of the present invention, a process for producing polycarbonate is provided, which comprises subjecting diphenyl polycarbonate and an alcohol such as bisphenol A, etc. as raw materials to polycondensation reaction at elevated temperatures ranging from 200° C. to 300° C. in vacuum less than or equal to the atmospheric pressure in one or more horizontal cylindrical agitation reactors, as ganged together in series, without any agitator center shaft, with increasing liquid viscosity from 1 Pa·s to 5,000 Pa·s, thereby continuously producing polycarbonate.
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Harada Kazunori
Kinoshita Takatoshi
Motohiro Seiji
Antonelli Terry Stout & Kraus LLP
Boykin Terressa
Hitachi , Ltd.
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