U.S. patent application number 09/790514 was filed with the patent office on 2001-07-05 for process and apparatus for producing polycarbonate.
Invention is credited to Harada, Kazunori, Kinoshita, Takatoshi, Motohiro, Seiji.
Application Number | 20010007014 09/790514 |
Document ID | / |
Family ID | 18200672 |
Filed Date | 2001-07-05 |
United States Patent
Application |
20010007014 |
Kind Code |
A1 |
Kinoshita, Takatoshi ; et
al. |
July 5, 2001 |
Process and apparatus for producing polycarbonate
Abstract
A process for producing polycarbonate designed to improve the
quality of polycarbonate as a polymerization product polymer and
reduce the investment and operating costs is provided.
Polycarbonate is produced in two horizontal cylindrical agitation
reactors provided with agitation blades successively extended
through the vessel and partly with agitation blades having a screw
function, as horizontally ganged together in series without any
agitator center shaft, where the primary agitation reactor is a
uniaxial horizontal agitation reactor with the agitation blades
rotating at a low speed ranging from 1 rpm to 10 rpm, while keeping
a clearance between the inner wall of the vessel ad the agitation
blades in a range of 1 mm to 50 mm, and the secondary agitation
reactor is a biaxial horizontal agitation reactor with agitation
blades provided horizontally and in parallel, without any rotating
center shaft, which conducts treatment by agitation at a low speed
ranging from 1 rpm to 15 rpm.
Inventors: |
Kinoshita, Takatoshi;
(Kudamatsu-shi, JP) ; Harada, Kazunori;
(Kudamatsu-shi, JP) ; Motohiro, Seiji;
(Kudamatsu-shi, JP) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
18200672 |
Appl. No.: |
09/790514 |
Filed: |
February 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09790514 |
Feb 23, 2001 |
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09486913 |
Oct 12, 2000 |
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09486913 |
Oct 12, 2000 |
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PCT/JP98/05245 |
Nov 20, 1998 |
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Current U.S.
Class: |
528/196 ;
422/134; 422/135; 422/137; 422/138 |
Current CPC
Class: |
B01F 2215/0495 20130101;
B01F 27/703 20220101; B01F 2215/0427 20130101; B01F 27/13 20220101;
B01F 2215/0481 20130101; C08G 64/205 20130101; B01F 27/70 20220101;
C08G 64/307 20130101; B01F 27/702 20220101 |
Class at
Publication: |
528/196 ;
422/134; 422/135; 422/137; 422/138 |
International
Class: |
C08G 064/30; C08G
064/04; C08G 064/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 1997 |
JP |
09-327582 |
Claims
What is claimed is:
1. An apparatus for producing polycarbonate, comprising: a first
stage reactor and a second stage reactor, and supply structure for
supplying diphenyl carbonate and an alcohol to the first stage
reactor and a mixed liquid from the first stage reactor to the
second stage reactor, wherein the first stage reactor is a uniaxial
horizontal agitation reactor comprising a horizontal cylindrical
vessel and agitation blades annularly distributed and successively
arranged through the vessel and secured at positions deviated from
a rotating axis toward the inner wall of the vessel without any
agitator center shaft, wherein the second stage reactor is a
horizontal biaxial agitation reactor with lattice blades, wherein
each of the first and second stage reactors includes a heater for
heating the respective stages to a temperature ranging from
200.degree. C. to 300.degree. C., and wherein each of the first and
second stage reactors includes structure to provide a pressure in
the respective reactor equal to or less than atmospheric pressure,
so as to thereby conduct polycondensation reaction of the diphenyl
carbonate and the alcohol and continuously produce
polycarbonate.
2. An apparatus for producing polycarbonates according to claim 1,
wherein the alcohol is bisphenol A.
3. A process for producing polycarbonate, which comprises a first
step of subjecting a mixed liquid of diphenyl carbonate and an
alcohol to agitating and mixing treatment in a uniaxial horizontal
agitation reactor without any agitator center shaft and a second
step of subjecting the mixed liquid from the first step to
agitation and mixing treatments in a horizontal biaxial agitation
reactor with lattice blades, both steps being carried out at
elevated temperatures ranging from 200.degree. C. to 300.degree. C.
in vacuum less than or equal to the atmospheric pressure with
increasing viscosity from 1 Pa.multidot.s to 5,000 Pa.multidot.s,
thereby conducting polycondensation reaction of the mixed liquid
and continuously producing polycarbonate.
4. The process for producing polycarbonate according to claim 3,
wherein said alcohol is bisphenol A.
Description
[0001] This application is a Divisional application of Ser. No.
09/486,913, filed Oct. 12, 2000, which is an application filed
under 35 USC 371 of International application No. PCT/JP98/05245,
filed Nov. 20, 1998.
TECHNICAL FIELD
[0002] 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
[0003] 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.
[0004] 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.
[0005] A spectacle rim-formed polymerization apparatus as disclosed
in FIG. 2.49(b), C1-43, C.multidot.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.
DISCLOSURE OF THE INVENTION
[0006] 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.
[0007] 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.
[0008] 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.degree. C. to 300.degree. 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.multidot.s to 5,000 Pa.multidot.s, thereby continuously
producing polycarbonate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic process diagram showing one embodiment
of the present process for producing polycarbonate.
[0010] FIG. 2 is a side view showing one embodiment of the
agitation blade structure of a primary agitation reactor.
[0011] FIGS. 3 to 7 are front views each showing embodiments of
partition plates.
[0012] FIG. 8 is a mixing characteristic diagram showing one
example of delta response curve.
[0013] FIG. 9 is a characteristic diagram showing one example of
relations between the viscosity and the number of theoretical
plates.
[0014] FIG. 10 is a characteristic diagram showing one example of
relations between the viscosity and the miscibility.
BEST MODE FOR CARRYING OUT THE INVENTION
[0015] Lattice blade polymerization apparatus is an agitation
reactor having rectangular frames as ganged together without any
agitator center shaft, as disclosed, for example, in JP-B-6-21159,
which can show a curve along the theoretical values.
[0016] For continuous treatment of a highly viscous liquid, it is
obvious from said fact that agitation blades without any agitator
center shaft have a better-miscibility and can contribute to
improvement of product liquid quality. Therefore, for continuous
production of polycarbonate from diphenyl carbonate and an alcohol
such as bisphenol A, etc. as raw materials with elevated liquid
viscosity, it is preferable to conduct polycondensation
continuously in one or more horizontal cylindrical agitation
reactors, as ganged together in series, without any agitator center
shaft, at elevated temperature ranging from 200.degree. C. to
300.degree. C. in vacuum less than or equal to the atmospheric
pressure with increasing liquid viscosity from 1 Pa.multidot.s to
5,000 Pa.multidot.s.
[0017] FIG. 9 shows test data of miscibilities of various
horizontal agitation reactors in comparison.
[0018] The larger the number of theoretical plates per unit stage,
the better the miscibility and the smaller the apparatus size, i.e.
the more economical. In FIG. 9, the uniaxial agitation reactor is
an agitation reactor without any agitator center shaft, where
agitation blades are continuously extended, while keeping the
clearance between the blade outer edges and the inner wall of the
vessel in a range of 1 mm-50 mm all over the inner surface of the
vessel. It is obvious from the result of said data that the
uniaxial agitation reactor can involve larger numbers of perfect
mixing vessels than that of the spectacle rim-formed polymerization
apparatus and thus has a better miscibility. FIG. 10 also shows
miscibilities. It is obvious therefrom that at a higher viscosity
than 400 Pa.multidot.s-600 Pa.multidot.s the miscibility of
spectacle rim-formed blades becomes poorer than that of lattice
blades. That is, it is obvious from the test data of FIGS. 9 and 10
that a horizontal agitation reactor without any agitator center
shaft is more effective for treating a highly viscous liquid
ranging from 1 Pa.multidot.s to 5,000 Pa.multidot.s.
[0019] FIG. 1 shows one embodiment of a process for producing
polycarbonate. In a continuous process for producing polycarbonate
from diphenyl carbonate and bisphenol A as raw materials by
transesterification, the liquid viscosity will increase with the
progress of reaction. Prepolymer having a viscosity of 1
Pa.multidot.s or higher obtained by the initial polycondensation
reaction at the preliminary stage is continuously fed to primary
agitation reactor 1 by pump 6. The agitation reactor for this
purpose is a horizontal agitation reactor in an agitation structure
without any agitator center shaft, as shown, for example, in FIGS.
2 to 7. Rotating axes 19 at both ends are connected to end plates
22, respectively, and both end plates are secured to each other by
a few reinforcing members 24. A plurality of blade partition plates
10 to 13 having different shapes depending on liquid viscosity
ranges are provided in the vertical direction to reinforcing member
24 between both end plates 22 to prevent the liquid from short pass
in the longitudinal direction and arranged at broader and broader
distances in proportion to increasing viscosity ranges. Numeral 12
designates an intermediate plate.
[0020] Agitation blades 15, 16, 17 and 18 have different blade
widths depending upon the liquid viscosity ranges and different
numbers of blades provided around the inner wall. Agitation blades
are continuously extended and arranged in the longitudinal
direction, while keeping small clearances ranging from 1 mm to 50
mm from the inner wall of vessel 50. Rotating axes rotate at a
lower speed of 1 rpm-10 rpm in comparison with a speed of 15 rpm-20
rpm as used in the case of the polymerization apparatus with
spectacle rim-formed blades. As a result, the agitation power can
be reduced to a few tenths. Scraper blades 20 and 21 provided on
the outer side of both end plates 22, respectively, have a screw
function of pushing the liquid back inwardly, while keeping a small
clearance from the inner wall of the vessel proper.
[0021] The liquid having a viscosity of about 1,000 Pa.multidot.s
discharged from the primary agitation reactor 1 is fed to secondary
agitation reactor 2 by pump 6. The secondary agitation reactor is a
biaxial agitation reactor provided with successively linked
agitation blades of rectangular frames horizontally and in parallel
without any agitator center shaft, as disclosed in JP-B-6-21159.
The reaction further proceeds in this reactor, where the liquid
viscosity is elevated to about 5,000 Pa.multidot.s, continuously
producing polymers.
[0022] In both agitation reactors, polycondensation reaction is
carried out at elevated temperatures ranging from 200.degree. C. to
350.degree. C. in vacuum ranging from the atmospheric pressure to
0.1 Torr. Phenol as a reaction by product is discharged from the
agitation reactors as overhead vapor to the system outside after
condensation in condenser 4.
[0023] According to another embodiment, the same type as that of
primary agitation reactor 1 is used for secondary agitation reactor
2, where blade partition plates having different shapes depending
upon the liquid viscosity ranges are arranged at broader and
broader distances in proportion thereto. As a result, the agitation
power can be further reduced.
[0024] According to the present invention, the product liquid
quality can be improved by using a horizontal agitation reactor or
reactors with successively linked agitation blades without any
rotating center shaft. The present invention can also provide a
process for producing polycarbonate, which can reduce the
investment and operating costs.
* * * * *