U.S. patent application number 09/509946 was filed with the patent office on 2003-08-21 for twin screw extruder, method of making aromatic polycarbonate using a twin screw extruder, and method of removing volatiles from an aromatic polycarbonate melt.
Invention is credited to HATONO, KAZUKI, ITO, EIJI, SASAKI, KATSUSHI, SAWAKI, TORU, SIMONARU, MASASI.
Application Number | 20030154859 09/509946 |
Document ID | / |
Family ID | 16750406 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030154859 |
Kind Code |
A1 |
SIMONARU, MASASI ; et
al. |
August 21, 2003 |
TWIN SCREW EXTRUDER, METHOD OF MAKING AROMATIC POLYCARBONATE USING
A TWIN SCREW EXTRUDER, AND METHOD OF REMOVING VOLATILES FROM AN
AROMATIC POLYCARBONATE MELT
Abstract
An aromatic polycarbonate extruder which is a twin screw
extruder for kneading components into a molten aromatic
polycarbonate, the extruder comprising at least one module
consisting of a kneading unit, a material seal unit, a back
kneading unit and a full-flight unit which are arranged from an
upstream side to a downstream side and a method of kneading
components into an aromatic polycarbonate by using the above
extruder. The present invention can provide a kneading apparatus
and method for producing an aromatic polycarbonate which has an
extremely small content of foreign matter and is free from
residence deterioration such as coloration, cross-linking or
gelation when the aromatic polycarbonate is to be kneaded with
various components.
Inventors: |
SIMONARU, MASASI;
(IWAKUNI-SHI, JP) ; SAWAKI, TORU; (IWAKUNI-SHI,
JP) ; SASAKI, KATSUSHI; (IWAKUNI-SHI, JP) ;
HATONO, KAZUKI; (IWAKUNI-SHI, JP) ; ITO, EIJI;
(IWAKUNI-SHI, JP) |
Correspondence
Address: |
SUGHRUE MION ZINN
MACPEAK & SEAS
2100 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20037
US
|
Family ID: |
16750406 |
Appl. No.: |
09/509946 |
Filed: |
April 4, 2000 |
PCT Filed: |
August 3, 1999 |
PCT NO: |
PCT/JP99/04191 |
Current U.S.
Class: |
95/149 ; 425/203;
425/376.1 |
Current CPC
Class: |
B29C 48/402 20190201;
B29C 48/55 20190201; B29C 67/246 20130101; B29C 48/395 20190201;
B29C 48/404 20190201; B29C 48/767 20190201; B29K 2069/00 20130101;
B29C 48/762 20190201; B29K 2105/0005 20130101; B29C 48/03 20190201;
B29C 48/268 20190201; B29C 48/29 20190201; Y10S 425/243 20130101;
B29C 48/565 20190201 |
Class at
Publication: |
95/149 ; 425/203;
425/376.1 |
International
Class: |
B01D 047/00; B29C
047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 4, 1998 |
JP |
10-220392 |
Claims
1. An aromatic polycarbonate extruder which is a twin screw
extruder for kneading components into a molten aromatic
polycarbonate, the extruder comprising at least one module
consisting of a kneading unit, a material seal unit, a back
kneading unit and a full-flight unit which are arranged from an
upstream side to a downstream side.
2. The extruder of claim 1, wherein the material seal unit is a
seal ring unit.
3. The extruder of claim 1, wherein the material seal unit is a
back flight unit.
4. The extruder of claim 1, wherein a component supply port is
formed in the area of the kneading unit.
5. The extruder of claim 1, wherein a vent port is formed in the
area of the full-flight unit.
6. The extruder of claim 1, wherein at least one component selected
from the group consisting of a terminal OH group capping agent,
catalyst deactivator, devolatilizing agent and resin additives is
kneaded into the aromatic polycarbonate.
7. The extruder of claim 1 comprising 2 to 8 of the module.
8. An aromatic polycarbonate extruder which is a twin screw
extruder for kneading components into a molten aromatic
polycarbonate, which extruder comprising at least one module
consisting of a neutral kneading unit or forward kneading unit, a
back kneading unit and a full-flight unit which are arranged from
an upstream side to a downstream side.
9. The extruder of claim 8, wherein a component supply port is
formed in the area of the neutral kneading unit or the forward
kneading unit.
10. The extruder of claim 8, wherein a vent port is formed in the
area of the full-flight unit.
11. An aromatic polycarbonate extruder which is a twin screw
extruder for kneading compounds into a molten aromatic
polycarbonate, which extruder comprising at least one module
consisting of material seal unit a back kneading unit and a
full-flight unit which are conjoined from an upstream side to a
downstream side.
12. The extruder of claims 1 or 8, wherein the aromatic
polycarbonate is a polycarbonate produced by melt polymerizing an
aromatic dihydroxy compound and a carbonic acid diester compound in
the presence of an ester exchange catalyst.
13. A method of kneading components into an aromatic polycarbonate
using a twin screw extruder comprising at least one module
consisting of a kneading unit, a material seal unit, a back
kneading unit and a full-flight unit which are arranged from an
upstream side to a downstream side, the method comprising the steps
of: (1) supplying the components to the area of the kneading unit
of the module of the twin screw extruder; and (2) discharging
volatile components from the area of the full-flight unit of the
module of the twin screw extruder as required.
14. The kneading method of claim 13, wherein at least one component
selected from the group consisting of a terminal OH group capping
agent, catalyst deactivator, devolatilizing agent and resin
additives is kneaded into the aromatic polycarbonate.
15. The method of claim 13, wherein at least one component selected
from the group consisting of a catalyst deactivator, devolatilizing
agent and resin additives is kneaded into the aromatic
polycarbonate.
16. The method of claim 13, wherein the component is water as a
devolatilizing component or water containing a catalyst
deactivator.
17. The method of claim 16, wherein water as adevolatilizing
component or water containing a catalyst deactivator is supplied to
the area of the kneading unit at an absolute pressure of 0.3 to 10
MPa.
18. A method of kneading components into an aromatic polycarbonate
using a twin screw extruder comprising at least one module
consisting of a neutral kneading unit or forward kneading unit, a
back kneading unit and a full-flight unit which are arranged from
an upstream side to a downstream side, the method comprising the
steps of: (1) supplying the components to the area of the neutral
kneading unit or forward kneading unit of the module of the twin
screw extruder; and (2) discharging volatile components from the
area of the full-flight unit of the module of the twin screw
extruder as required.
19. The kneading method of claim 18, wherein at least one component
selected from the group consisting of a terminal OH group capping
agent, catalyst deactivator, devolatilizing agent and resin
additives is kneaded into the aromatic polycarbonate.
20. The kneading method of claim 18, wherein the component is a
terminal OH group capping agent.
21. The kneading method of claim 18, wherein the component is a
resin additive.
22. The kneading method of claim 13 or 18, wherein the aromatic
polycarbonate is a polycarbonate produced by melt polymerizing an
aromatic dihydroxy compound and a carbonic acid diester compound in
the presence of an ester exchange catalyst.
23. A method of removing volatile components from a twin screw
extruder together with water vapor by supplying water to the twin
screw extruder and kneading it into a molten aromatic
polycarbonate, the method comprising the steps of: supplying water
to the twin screw extruder at an absolute pressure of 0.3 to 10
MPa; and discharging water vapor and volatile components from the
extruder at an absolute pressure of 1.333.times.10 Pa to
1.013.times.10.sup.5 Pa.
24. The removing method of claim 23, wherein water contains a
catalyst deactivator.
25. The removing method of claim 23, wherein the amount of water is
0.1 to 20 parts by weight based on 100 parts by weight of the
aromatic polycarbonate.
26. The removing method of claim 23, wherein water contains a
catalyst deactivator in an amount of 0.5 to 50 equivalent based on
1 equivalent of a polymerization catalyst contained in the aromatic
polycarbonate.
27. The removing method of claim 23, wherein the time required to
knead water in the twin screw extruder is 0.05 to 100 seconds.
28. The removing method of claim 23, wherein the twin screw
extruder comprises at least one module consisting of a kneading
unit, a material seal unit, a back kneading unit and a full-flight
unit which are arranged from an upstream side to a downstream side,
water is supplied to the area of the kneading unit of the module,
and water vapor is discharged from the area of the full-flight unit
to the outside of the extruder together with volatile
components.
29. The method of claim 23, wherein the aromatic polycarbonate is a
polycarbonate produced by melt polymerizing an aromatic dihydroxy
compound and a carbonic acid diester compound in the presence of an
ester exchange catalyst.
30. A twin screw extruder for kneading a thermoplastic resin, which
comprises at least one module consisting of a material seal unit, a
back kneading unit and a full-flight unit which are arranged from
an upstream side to a downstream side.
31. The twin screw extruder of claim 30, wherein the module has a
kneading unit on an upstream side of the material seal unit.
32. The twin screw extruder of claim 30, wherein the module has a
full-flight unit on an upstream side of the material seal unit.
33. The twin screw extruder of claim 30 for kneading components
into a thermoplastic resin.
34. A twin screw extruder for kneading a thermoplastic resin
comprising a module consisting of a neutral kneading unit or
forward kneading unit, a back kneading unit and a full-flight unit
which are arranged from an upstream side to a downstream side.
35. The twin screw extruder of claim 34 for kneading components
into a thermoplastic resin.
36. A method of removing volatile components contained in an
aromatic polycarbonate using a twin screw extruder and water as a
devolatilizing agent, wherein a vacuum collection system comprising
the following steps is installed between the vent port of the
extruder and a vacuum pump: 1) the step of condensing water vapor
and volatile components by introducing these vapor generated in the
extruder into a scrubber which uses cool water as a scrubbing
solution and contacting them to water having a temperature below
its boiling point at the operation pressure of the scrubber; 2) the
step of separating solid volatile components from the scrubbing
solution containing the solidified volatile components discharged
from the scrubber; 3) the step of cooling water from which the
solidified volatile components have been separated to a temperature
below its boiling point at the operation pressure of the scrubber;
and 4) the step of circulating the cooled water to the
scrubber.
37. The removing method of claim 36, wherein the aromatic
polycarbonate is a polycarbonate produced by melt polymerizing an
aromatic dihydroxy compound and a carbonic acid diester compound in
the presence of an ester exchange catalyst.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and a method
for kneading components into an aromatic polycarbonate. More
specifically, it relates to a kneading apparatus and method which
have an excellent kneading effect, suppress coloration,
crosslinking and gelation due to the residence of a resin and can
obtain a product having a small content of foreign matter when
components to be kneaded, such as a terminal OH group capping
agent, catalyst deactivator, devolatilizing agent and resin
additives are added to and kneaded into an aromatic polycarbonate.
Particularly, it relates to a twin screw extruder for adding and
kneading the above components into an aromatic polycarbonate and
the improvement of the extruder.
[0003] 2. Prior Art
[0004] Aromatic polycarbonates are widely used for various purposes
due to their excellent mechanical properties such as impact
resistance and transparency. Known methods for producing such
aromatic polycarbonates include an interfacial polymerization
method in which a dihydroxy compound and phosgene are directly
reacted with each other, a melt polymerization method in which an
ester exchange reaction between a dihydroxy compound and a carbonic
acid diester is carried out under heating and reduced pressure, and
the like.
[0005] An aromatic polycarbonate obtained by polymerization is
generally kneaded with various components using an intermeshing
twin screw extruder. In this kneading step, the coloration,
crosslinking and gelation of the aromatic polycarbonate occur, and
the content of foreign matter contained in the aromatic
polycarbonate increases, thereby exerting a great influence upon
the quality of a final product.
[0006] These problems are serious for an aromatic polycarbonate
which has recently been used in optical recording media that is
required high recording density and high accuracy, such as a DVD,
MO and CDR because such problems as coloration and gelation have a
direct influence upon the optical properties such as a block error
rate and mechanical properties such as tensile strength, flexural
strength and toughness of a final product.
[0007] It is an object of the present invention to provide a
kneading apparatus and method for producing an aromatic
polycarbonate which has an extremely small content of foreign
matter and is free from residence deterioration such as coloration,
crosslinking or gelation when the aromatic polycarbonate is to be
kneaded with various components.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0008] FIGS. 1 (a) to (g) are oblique, side and front views showing
the configurations of various segments fitted onto the each screw
shaft of a twin screw extruder (in the present invention, at least
one `segment` is used to construct an `unit` constituting a
`module`);
[0009] FIG. 2 is a structural diagram typically showing the
arrangement of the modules of the twin screw extruder of the
present invention;
[0010] FIG. 3 is a schematic diagram of a system for collecting
volatile components accompanyed with water vapor discharged from
the twin screw extruder;
[0011] FIG. 4 is a diagram of a scrubber body and spraies in the
collection system;
[0012] FIG. 5 is a diagram showing the form of conical spray
containing liquid drops inside a spray cone (solid conical spray);
and
[0013] FIG. 6 is a diagram showing the form of conical spray whose
inside is hollow (hollow conical spray).
[0014] Reference numerals in FIGS. 3 to 5 denote the following
elements.
[0015] 1 vacuum generator (vacuum pump)
[0016] 2 vacuum line
[0017] 3 spray nozzle
[0018] 4 outlet for the vacuum line
[0019] 5 inlet for the vapor line
[0020] 6 outlet for the scrubbing solution line
[0021] 7 scrubbing solution storage tank
[0022] 8 installation angle between scrubber and vapor inlet
line
[0023] 9 vapor line
[0024] 10 scrubber
[0025] 11 scrubbing solution line
[0026] 12 scrubbing solution line
[0027] 13 scrubbing solution pump
[0028] 14 separator (filter)
[0029] 15 scrubbing solution line
[0030] 16 scrubbing solution line
[0031] 17 scrubbing solution discharging line
[0032] 18 cooler
[0033] 19 flow meter
[0034] 20 steam jacket
[0035] 21 twin screw extruder
[0036] 22 liquid injection nozzle
[0037] 23 to 25 liquid injection nozzle
[0038] Terms for the units of an extruder and related to these in
this specification mean as follows. FIGS. 1(a) to 1(g) are used
when needed for explanation.
[0039] A figure on the left side of FIG. 1(a) is a perspective view
of a spindle-shaped flat plate fitted onto the single screw shaft
of an extruder, a figure in the middle is a side view of the
spindle-shaped flat plate fitted onto the screw shaft of the
extruder when seen from a direction perpendicular to the center of
the screw shaft of the extruder and a figure on the right side is a
front view of the spindle-shaped flat plate fitted onto the screw
shaft of the extruder when seen from the direction of the center of
the screw shaft of the extruder (on a downstream side).
[0040] FIG. 1(b) is a combination of oblique, side and front views
of a back kneading segment.
[0041] FIG. 1(c) is a combination of oblique, side and front views
of a forward kneading segment.
[0042] FIG. 1(d) is a combination of oblique, side and front views
of a neutral kneading segment.
[0043] FIG. 1(e) is a combination of oblique, side and front views
of a seal ring segment.
[0044] FIG. 1(f) is a combination of oblique, side and front views
of a full-flight segment.
[0045] FIG. 1(g) is a combination of oblique, side and front views
of a back flight segment.
[0046] A resin moves from left to right in the oblique views of
FIGS. 1(a) to 1(g). In this specification, the long axis and short
axis of the flat plate mean lengths indicated by numerals 1 and 2
in the front view of FIG. 1(a).
[0047] The term "agitation elements" means a screw segment having a
specific shape for the purpose of stirring, kneading and
transferring a resin according to the function and purpose of the
segment of a twin screw extruder, such as a back kneading segment,
forward kneading segment or neutral kneading segment which will be
described hereinafter.
[0048] The expression "on a downstream side" means a downstream
side of a flow of a resin to be kneaded.
[0049] Back Kneading Unit;
[0050] As shown in FIG. 1(b), the "back kneading segment" means an
agitation element constructed by combining together a plurality of
(generally 5 to 13) flat plates having basically a spindle shape
when seen from a transverse direction of the twin screw extruder.
The spindle-shaped flat plates are combined together in a direction
opposite to the traveling direction of the resin in such a manner
that they are shifted from one another at a phase angle larger than
0.degree. and smaller than 90.degree. in a negative direction when
the rotating direction of the screw shaft of the extruder is
positive, and the center of the screw shaft passes through an
intersection point between the long axis and the short axis of each
of the spindle-shaped flat plates in a direction perpendicular to
the spindle-shaped flat plate. In the twin screw extruder, the
agitation units are set such that they engage with one another. In
the present invention, a group consisting of at least one back
kneading segment is called "back kneading unit".
[0051] Forward Kneading Unit;
[0052] As shown in FIG. 1(c), the "forward kneading segment" means
an agitation element constructed by combining together a plurality
of (generally 5 to 13) flat plates having basically a spindle shape
when seen from a transverse direction of the twin screw extruder.
The spindle-shaped flat plates are combined together in a direction
opposite to the traveling direction of the resin to be kneaded in
such a manner that they are shifted from one another at a phase
angle larger than 0.degree. and smaller than 90.degree. in a
positive direction when the rotating direction of the screw shaft
of the extruder is positive and, and the center of the screw shaft
passes in through an intersection point between the long axis and
the short axis of each of the spindle-shaped flat plates in a
direction perpendicular to the spindle-shaped flat plate. In the
twin screw extruder, the agitation units are set such that they
engage with one another. In the present invention, a group
consisting of at least one forward kneading segment is called
"forward kneading unit".
[0053] Neutral Kneading Unit;
[0054] As shown in FIG. 1(d), the "neutral kneading segment" means
an agitation element constructed by combining together a plurality
of (generally 5 to 13) flat plates having basically a spindle shape
when seen from a transverse direction to the thickness of the twin
screw extruder. The spindle-shaped flat plates are combined
together in such a manner that they are substantially shifted from
one another at a phase angle of 90.degree. in the rotating
direction of the screw shaft of the extruder, and the center of the
screw shaft passes through an intersection point between the long
axis and the short axis of each of the spindle-shaped flat plates
in a direction perpendicular to the spindle-shaped flat plate. In
the twin screw extruder, the agitation units are set such that they
engage with one another. In the present invention, a group
consisting of at least one neutral kneading segment is called
"neutral kneading unit".
[0055] Full-Flight Unit;
[0056] As shown in FIG. 1(f), the "full-flight segment" means an
agitation element figured a spiral rotary blade portion of the
extruder, which is formed spirally around the screw shaft of the
extruder without a break and whose spiral direction is set to move
the resin in the traveling direction of the resin by the rotation
of the screw shaft of the extruder. A pair of such segments locate
on each screw shaft of the twine screw extruder so as to mesh with
each other (segment). In the present invention, a group consisting
of at least one full-flight segment is called "full-flight
unit".
[0057] Back Flight Unit;
[0058] As shown in FIG. 1(g), the "back flight segment" means an
agitation element figured a spiral rotary blade portion of the
extruder, which is formed spirally around the screw shaft of the
extruder without a break and whose spiral direction is set to move
the resin in a backward direction of the resin by the rotation of
the screw shaft of the extruder. A pair of such segments locate on
each screw shaft of the twin screw extruder so as to mesh with each
other (segment). In the present invention, a group consisting of at
least one back flight segment is called "back flight unit".
[0059] Kneading Unit;
[0060] The "kneading unit" means an agitation element of a twin
screw extruder, which is installed to knead the components of the
present invention and is constructed by installing the back
kneading unit, the forward kneading unit and the neutral kneading
unit in a desired order repeatedly as required.
[0061] Seal Ring Unit;
[0062] As shown in FIG. 1(e), the "seal ring unit" means an
agitation unit composed of at least one flat plate having a
circular shape in a transverse direction. The center of the screw
shaft of the extruder passes through the center of the disk in a
direction perpendicular to the disk. The seal ring unit prevents
the traveling of the resin and has such a structure that the resin
passes through a clearance between a cylinder body and the seal
ring unit.
[0063] Material Seal Unit;
[0064] The "material seal unit" means an agitation element of a
twin screw extruder, which is installed to enable an upstream
portion and a downstream portion thereof to take different
operation pressures. It means an agitation element including a
portion whose space is substantially completely filled with the
resin to be kneaded when the section of the extruder is seen, and
the sealing ring unit or the back flight unit can be the material
seal unit.
[0065] The expression "intermeshing twin screw extruder" as used
herein means an extruder having excellent transfer, reaction,
kneading and devolatilizing functions, whose right and left shafts
are meshed with each other to obtain a self-cleaning effect and
remove a residence portion of the resin.
[0066] The expression "resin filling rate" means the ratio of the
volume of a molten resin to the volume of a space in the twin screw
extruder.
Means for Solving the Problem
[0067] Studies conducted by the inventors of the present invention
have revealed that the above object of the present invention is
attained by using a module constructed by selecting specific units
from various units described above to be fitted onto the screw
shaft of an extruder and combining these when various additive
components are to be kneaded into an aromatic polycarbonate using a
twin screw extruder.
[0068] Therefore, according to the present invention, there is
provided an aromatic polycarbonate extruder which is a twin screw
extruder for kneading components into a molten aromatic
polycarbonate, the extruder comprising at least one module (to be
referred to as "module A" hereinafter) consisting of a kneading
unit, a material seal unit, a back kneading unit and a full-flight
unit which are arranged from an upstream side to a downstream
side.
[0069] According to the present invention, there is further
provided an aromatic polycarbonate extruder which is a twin screw
extruder for kneading components into a molten aromatic
polycarbonate, the extruder comprising at least one module (to be
referred to as "module B" hereinafter) consisting of a neutral
kneading unit or forward kneading unit, a back kneading unit and a
full-flight unit which are arranged from a downstream side to an
upstream side.
[0070] According to the present invention, there is further
provided a method of kneading components into an aromatic
polycarbonate using a twin screw extruder comprising at least one
of the module A and the module B, the method comprising supplying
the components to a specific area of the module and discharging
volatile components from a specific area of the module as
required.
[0071] The aromatic polycarbonate kneading apparatus and method of
the present invention will be described in detail hereinunder.
[0072] A description is first given of the aromatic polycarbonate
in the present invention.
[0073] In the present invention, residence deterioration such as
the coloration, crosslinking or gelation of a resin is suppressed
by using the above twin screw extruder when the components are
kneaded into the resin and a resin having an extremely small
content of foreign matter can be produced. As the aromatic
polycarbonate resin to be supplied to an intermeshing twin screw
extruder, aromatic polycarbonate resins obtained by various known
methods per se may be used. They include, for example, what are
produced by a reaction between a divalent phenol and a carbonate
precursor such as phosgene in a solvent such as methylene chloride
in the presence of a known acid receptor and a molecular weight
control agent (interfacial polymerization) and what are produced by
melt polycondensing an aromatic diol compound and a carbonic acid
diester in the presence of an ester exchange catalyst or the like
(melt polymerization). Particularly when polymerization is carried
out continuously in accordance with the latter method, if the twin
screw extruder must be stopped to remove foreign matter generated
in the twin screw extruder, the polycondensation step must be
stopped immediately because the polycondensation step and the
kneading step using the twin screw extruder are directly connected
to each other. Therefore, a great effect can be obtained by
eliminating the need to stop the operation of the twin screw
extruder which is realized by suppressing the generation of foreign
matter in the twin screw extruder. Consequently, the present
invention is advantageously applied to an aromatic polycarbonate
which is produced by the melt polymerization method.
[0074] Illustrative examples of the aromatic diol compound used in
the melt polycondensation include bis(4-hydroxyphenyl)methane,
2,2-bis(4-hydroxyphenyl)propane,
2,2-bis(4-hydroxy-3-methylphenyl)propane- ,
4,4-bis(4-hydroxyphenyl)heptane,
2,2-bis(4-hydroxy-3,5-dichlorophenyl)pr- opane,
2,2-bis(4-hydroxy-3,5-dibromophenyl)propane,
bis(4-hydroxyphenyl)oxide, bis(3,5-dichloro-4-hydroxyphenyl)oxide,
p,p'-dihydroxydiphenyl, 3,3'-dichloro-4, 4'-dihydroxydiphenyl,
bis(hydroxyphenyl)sulfone, resorcinol, hydroquinone,
1,4-dihydroxy-2,5-dichlorobenzene, 1,4-dihydroxy-3-methylbenzene,
bis(4-hydroxyphenyl)sulfide and bis(4-hydroxyphenyl)sulfoxide. Out
of these, 2,2-bis(4-hydroxyphenyl)propane is particularly
preferred.
[0075] Illustrative examples of the carbonic acid diester include
diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate,
m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl)carbonate,
dimethyl carbonate, diethyl carbonate, dibutyl carbonate and
dicyclohexyl carbonate. Out of these, diphenyl carbonate is
particularly preferred.
[0076] The aromatic polycarbonate of the present invention may
contain an aliphatic diol such as ethylene glycol, 1,4-butanediol,
1,4-cyclohexanedimethanol or 1,10-decanediol, dicarboxylic acid
such as succinic acid, isophthalic acid,
2,6-naphthalenedicarboxylic acid, adipic acid,
cyclohexanecarboxylic acid or terephthalic acid, oxyacid such as
lactic acid, p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, or
the like as required while it is produced. The aromatic
polycarbonate of the present invention may be a copolymer of
these.
[0077] An ester exchange catalyst is used for the production of an
aromatic polycarbonate by a melt polymerization method as described
above. The ester exchange catalyst is generally an alkali metal
compound, alkali earth metal compound or nitrogen-containing basic
compound.
[0078] The alkali metal compound used as a catalyst is, for
example, a hydroxide, bicarbonate, carbonate, acetate, nitrate,
nitrite, sulfite, cyanate, thiocyanate, stearate, borohydride,
benzoate, hydrogenphosphate, bisphenol salt, phenol salt or the
like of an alkali metal.
[0079] Illustrative examples of the alkali metal compound include
sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium
bicarbonate, potassium bicarbonate, lithium bicarbonate, sodium
carbonate, potassium carbonate, lithium carbonate, sodium acetate,
potassium acetate, lithium acetate, sodium nitrate, potassium
nitrate, lithium nitrate, sodium nitrite, potassium nitrite,
lithium nitrite, sodium sulfite, potassium sulfite, lithium
sulfite, sodium cyanate, potassium cyanate, lithium cyanate, sodium
thiocyanate, potassium thiocyanate, lithium thiocyanate, sodium
stearate, potassium stearate, lithium stearate, sodium borohydride,
potassium borohydride, lithium borohydride, sodium phenylborate,
sodium benzoate, potassium benzoate, lithium benzoate, disodium
hydrogenphosphate, dipotassium hydrogenphosphate, dilithium
hydrogenphosphate, disodium, dipotassium and dilithium salts of
bisphenol A, and sodium, potassium and lithium salts of phenol.
[0080] The alkali earth metal compound used as a catalyst is an
hydroxide, bicarbonate, carbonate, acetate, nitrate, nitrite,
sulfite, cyanate, thiocyanate, stearate, borohydride, benzoate,
bisphenol salt, phenol salt or the like of an alkali earth
metal.
[0081] Illustrative examples of the alkali earth metal compound
include calcium hydroxide, barium hydroxide, strontium hydroxide,
calcium bicarbonate, barium bicarbonate, strontium bicarbonate,
calcium carbonate, barium carbonate, strontium carbonate, calcium
acetate, barium acetate, strontium acetate, calcium nitrate, barium
nitrate, strontium nitrate, calcium nitrite, barium nitrite,
strontium nitrite, calcium sulfite, barium sulfite, strontium
sulfite, calcium cyanate, barium cyanate, strontium cyanate,
calcium thiocyanate, barium thiocyanate, strontium thiocyanate,
calcium stearate, barium stearate, strontium stearate, calcium
borohydride, barium borohydride, strontium borohydride, calcium
benzoate, barium benzoate, strontium benzoate, calcium salts,
barium salts and strontium salts of bisphenol A, and calcium salts,
barium salts and strontium salts of phenol.
[0082] The alkali metal compound or alkali earth metal compound is
preferably used in an amount of 1.times.10.sup.-8 to
5.times.10.sup.-5 equivalent in terms of elemental alkali metal or
elemental alkali earth metal contained in the catalyst based on 1
mol of the aromatic diol compound. The amount is more preferably
5.times.10.sup.-7 to 1.times.10.sup.-5 equivalent based on the same
standard.
[0083] Illustrative examples of the nitrogen-containing basic
compound as a catalyst include ammonium hydroxides having an alkyl,
aryl or alkylaryl group such as tetramethyl ammonium hydroxide
(Me.sub.4NOH), tetraethyl ammonium hydroxide (Et.sub.4NOH),
tetrabutyl ammonium hydroxide (Bu.sub.4NOH), benzyltrimethyl
ammonium hydroxide (.phi.-CH.sub.2(Me).sub- .3NOH) and
hexadecyltrimethyl ammonium hydroxide; tertiary amines such as
triethylamine, tributylamine, dimethylbenzylamine and
hexadecyldimethylamine; and basic salts such as tetramethyl
ammonium borohydride (Me.sub.4NBH.sub.4), tetrabutyl ammonium
borohydride (Bu.sub.4NBH.sub.4), tetrabutyl ammonium tetraphenyl
borate (Me.sub.4NBPh.sub.4) and tetrabutyl ammonium tetraphenyl
borate (Bu.sub.4NBPh.sub.4).
[0084] The above nitrogen-containing basic compound is preferably
used in an amount of 1.times.10.sup.-5 to 5.times.10.sup.-3
equivalent in terms of ammonium nitrogen atoms contained in the
nitrogen-containing basic compound based on 1 mol of the aromatic
diol compound. The amount is more preferably 2.times.10.sup.-5 to
5.times.10.sup.-4 equivalent, particularly preferably
5.times.10.sup.-5 to 5.times.10.sup.-4 equivalent based on the same
standard.
[0085] In the production of the aromatic polycarbonate, an alkali
metal salt of silicon, germanium or tin oxoacid may be optionally
used as a co-catalyst. Illustrative examples of the alkali metal
salt as a co-catalyst are enumerated in JP-A 7-268091 (the term
"JP-A" as used herein means an "unexamined published Japanese
patent application"). An undesirable side reaction such as a
branching reaction which readily occurs during a polycondensation
reaction, the formation of foreign matter or deterioration in the
apparatus at the time of molding can be suppressed effectively by
using these alkali metal salts (co-catalyst) without impairing the
rate of a terminal OH group capping reaction or polycondensation
reaction.
[0086] The co-catalyst is preferably existent in an amount of 50
mols (atoms) or less in terms of elemental metal such as silicon,
germanium or tin contained in the co-catalyst based on 1 mol (atom)
of the elemental alkali metal contained in the polycondensation
reaction catalyst. When the co-catalyst is used in an amount of
more than 50 mols (atoms) in terms of the elemental metal, the
polycondensation reaction rate slows down disadvantageously.
[0087] The co-catalyst is more preferably existent in an amount of
0.1 to 30 mols (atoms) in terms of the above elemental metal
contained in the co-catalyst based on 1 mol (atom) of the elemental
alkali metal contained in the polycondensation reaction
catalyst.
[0088] A catalyst system using the co-catalyst has such an
advantage that the polycondensation reaction and the terminal
capping reaction can be promoted swiftly and thoroughly by using
the co-catalyst in the polycondensation reaction. The co-catalyst
can suppress an undesirable side-reaction such as a branching
reaction which occurs in the polycondensation reaction system to a
low level.
[0089] In the present invention, equipment and a process used for
the production of a polycarbonate through an ester exchange
reaction between an aromatic dihydroxy compound and a carbonic acid
diester are not particularly limited, and conventionally known
equipment and processes may be used. When the ester exchange
reaction is carried out in a batch manner, two reactors are
generally installed in series, an agitation tank equipped with a
fractionating column is used as the former reactor and an agitation
tank without a fractionating column is used as the latter reactor
so that the reaction is carried out under different conditions. In
this case, it is preferred to connect these tanks to each other by
a pipe having a valve and to equip with a pump for transferring a
reaction solution as required so that the reaction product of the
former reactor is transferred to the latter reactor without being
exposed to the outside air and the reaction is carried in the
latter reactor until a desired degree of polymerization is
achieved.
[0090] When the ester exchange reaction is carried out in a
continuous matter, at least two reactors are generally installed in
series, adjacent reactors are connected to each other by a pipe
having a valve, equipped with a pump for transferring a reaction
solution as required, it is used to continuously supply raw
materials and a catalyst to the first reactor (while maintaining
the reactors under different conditions), and discharge
polycarbonate resens having a desired degree of polymerization from
the last reactor while maintaining the reactors under different
conditions.
[0091] The molar ratio of the carbonic acid diester to the aromatic
dihydroxy compound is changed by the efficiency of the
fractionating column, the reaction rate of the monomer in each of
the reactors and the amount of the OH terminal groups of the
polycarbonate to be obtained but it is generally 0.8 to 1.5,
preferably 0.95 to 1.1, more preferably 1.0 to 1.05.
[0092] The materials of devices used in the equipment are not
particularly limited but a material having a large iron content
should be avoided and nickel and stainless steel are preferred.
[0093] A detailed description is subsequently given of the
components to be added to the aromatic polycarbonate in the present
invention.
[0094] The expression "components" means components to be added to
and kneaded into an aromatic polycarbonate obtained by
polymerization to produce a polymer suitable for obtaining a molded
product of the aromatic polycarbonate. The components include (a) a
compound which is chemically bonded to the main chain of the
polymer, such as a terminal OH group capping agent, (b) a compound
which acts on a component contained in the polymer other than a
polymer to reduce, deactivate or change the function of the
component, such as a catalyst deactivator, (c) a compound which is
added to assist the removal of relatively volatile components such
as an eliminated component (such as phenol), monomer and
low-molecular weight oligomer contained in the polymer, such as a
devolatilizing agent, and (d) resin additives which are added to
improve the moldability of the aromatic polycarbonate and the
physical and chemical properties of a molded product. These
components will be described hereinunder.
[0095] (a) Terminal OH Group Capping Agent
[0096] The produced aromatic polycarbonate has an aromatic hydroxyl
group or its derivative group derived from an aromatic diol
compound which uses as a monomer in the melt polycondonsation. This
terminal OH group is preferably capped for stability. The terminal
OH group capping agent used for this purpose is an aromatic
compound having a group which can react with the terminal OH group.
Known compounds are used as the compound, as exemplified by the
derivatives of aliphatic aryl carboxylates and aromatic aryl
carboxylates and the derivatives of aliphatic aryl carbonates and
aromatic aryl carbonates such as methoxycarbonyl phenyl phenyl
carbonate and ethoxycarbonyl phenyl phenyl carbonate.
[0097] The terminal OH group capping agent is added in an amount of
0.3 to 2 mol equivalents based on 1 mol of the hydroxy terminal of
the aromatic polycarbonate. When the amount of the terminal capping
agent is smaller than 0.3 mol equivalent, a satisfactory terminal
capping effect cannot be obtained and when the amount is larger
than 2 mol equivalents, a surplus of the terminal capping agent
remains in the aromatic polycarbonate, thereby reducing quality
disadvantageously.
[0098] (b) Catalyst Deactivator
[0099] When a catalyst used for polymerization is contained in the
aromatic polycarbonate while it retains its activity, it exerts an
influence upon heat stability, color stability and hydrolysis
resistance. Therefore, it is preferred to deactivate the residual
polymerization catalyst.
[0100] Known catalyst deactivators for example, described in JP-A
8-59975 may be used effectively as the catalyst deactivator. Out of
these, ammonium salts, phosphonium salts and esters of sulfonic
acid are preferred. Illustrative examples of the catalyst
deactivator include esters, ammonium salts and phosphonium salts of
dodecylbezenesulfonic acid, esters, ammonium salts and phosphonium
salts of paratoluenesulfonic acid, and esters, ammonium salts and
phosphonium salts of benzenesulfonic acid. Out of these,
tetrabutylphosphonium salts of dodecylbenzenesulfonic acid and
tetrabutylammonium salts of paratoluenesulfonic acid are
particularly preferred.
[0101] Preferred sulfonic acid esters include methyl
benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate,
octyl benzenesulfonate, phenyl benzenesulfonate, methyl
paratoluenesulfonate, ethyl paratoluenesulfonate, butyl
paratoluenesulfonate, octyl paratoluenesulfonate and phenyl
paratoluenesulfonate.
[0102] The amount of the catalyst deactivator to be added to the
aromatic polycarbonate is 0.5 to 50 equivalent, preferably 0.5 to
10 equivalent, more preferably 0.8 to 5 equivalent based on 1
equivalent of a polycondensation catalyst such as an alkali metal
compound or alkali earth metal compound. This is equivalent to 0.01
to 500 ppm based on the aromatic polycarbonate.
[0103] The above catalyst deactivator may be directly kneaded into
the aromatic polycarbonate or may be kneaded as a solution in a
solvent. In this case, the solvent serves as a devolatilizing agent
to help the removal of volatile components contained in the
polymer.
[0104] The solvent used when the catalyst deactivator is kneaded
into the aromatic polycarbonate is preferably water, saturated
aliphatic hydrocarbon or aromatic hydrocarbon. Out of these, water
is particularly preferred.
[0105] The saturated aliphatic hydrocarbon preferably has a boiling
point at normal pressure of 30 to 270.degree. C., preferably 50 to
200.degree. C., more preferably 50 to 150.degree. C.
[0106] Illustrative examples of the saturated aliphatic hydrocarbon
include 2-methylbutane, pentane, 2,2-dimethylbutane,
2,3-dimethylbutane, hexane, 2-methylpentane, 3-methylpentane,
2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane,
3,3-dimethylpentane, heptane, 2-methylhexane, 3-methylhexane,
2,2,3-trimethylbutane, 2,2-dimethylhexane, 2,5-dimethylhexane,
3,4-dimethylhexane, hexamethylethane, 2-methylheptane,
4-methylheptane, octane, 2,2,4-trimethylpentane,
2,3,4-trimethylpentane, nonane, decane, undecane, dodecane,
tridecane, tetradecane, 1-pentadecane and the like.
[0107] The aromatic hydrocarbon preferably has a boiling point at
normal pressure of 80 to 270.degree. C., preferably 80 to
200.degree. C., more preferably 80 to 150.degree. C.
[0108] Illustrative examples of the aromatic hydrocarbon include
benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene,
2-ethyltoluene, 3-ethyltoluene, 4-ethyltoluene, cumene, mesitylene,
propylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene,
butylbenzene, sec-butylbenzene, tert-butylbenzene, o-cymene,
m-cymene, p-cymene, 1,2-diethylbenzene, 1,4-diethylbenzene,
1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene,
amylbenzene, 4-tert-butyltoluene, (2,2-dimethylpropyl)benzene,
isoamylbenzene, 5-tert-butyl-m-xylene, 1,3-diisopropylbenzene,
1,4-diisopropylbenzene, 1-phenylhexane, 1,2,4-trimethylbenzene,
1,3-di-tert-butylbenzene and the like.
[0109] Even when the added catalyst deactivator contains a volatile
compound or forms a thermal decomposition product by thermal
decomposition, they can be removed by evacuation at the same
time.
[0110] (c) Devolatilizing Agent
[0111] Illustrative examples of the devolatilizing agent include
water, nitrogen gas, the above saturated aliphatic hydrocarbon and
the above aromatic hydrocarbon. Out of these, water is economically
advantageous and particularly preferred.
[0112] Preferably, water used as the devolatilizing agent contains
substantially no metal ions or chlorine ions. Stated more
specifically, ion exchange water and distilled water are
preferred.
[0113] Even when the above devolatilizing agent contains a volatile
compound or forms a thermal decomposition product by thermal
decomposition, they can be removed by evacuation at the same
time.
[0114] The devolatilizing agent is added in an amount of 0.1 to 20
parts by weight based on 100 parts by weight of the aromatic
polycarbonate. When the amount of the devolatilizing agent is
smaller than 0.1 part by weight, the removal of volatile impurities
becomes unsatisfactory and when the amount is larger than 20 parts
by weight, the effect of removing impurities is not improved for
that amount, which is economically disadvantageous.
[0115] (d) resin additives
[0116] The resin additives are added to the aromatic polycarbonate
for specific purposes. The resin additives include, for example, a
thermal stabilizer, optical stabilizer, epoxy compound, ultraviolet
absorber, release agent, colorant, slip agent, antiblocking agent,
lubricant, organic filler, inorganic filler and the like. Other
polymers such as ABS resins and polyester resins may also be
added.
[0117] Out of these, a thermal stabilizer, ultraviolet absorber,
release agent and colorant are generally used and may be used in
combination of two or more. Illustrative examples of these
additives are given below.
[0118] Illustrative examples of the thermal stabilizer include
phosphorus compounds, phenol-based stabilizers, organic
thioether-based stabilizers, hindered amine-based stabilizers and
the like.
[0119] The ultraviolet absorber is a general ultraviolet absorber
exemplified by salicylic acid-based ultraviolet absorbers,
benzophenone-based ultraviolet absorbers, benzotriazole-based
ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers
and the like.
[0120] The release agent is a generally known release agent
exemplified by hydrocarbon-based release agents such as paraffins,
fatty acid-based release agents such as stearic acid, fatty acid
amide-based release agents such as stearic acid amide,
alcohol-based release agents such as stearyl alcohol and
pentaerythritol, fatty acid ester-based release agents such as
glycerin monostearate and pentaerythritol, silicone-based release
agents such as silicone oil, and the like.
[0121] The colorant is an organic or inorganic pigment or dye.
[0122] The above resin additives may be added to and kneaded into
the aromatic polycarbonate directly or after they are dispersed or
dissolved in a solvent as required.
[0123] In this respect, the solvent used for the addition and
kneading of the additives is water, the above saturated aliphatic
hydrocarbon or the above aromatic hydrocarbon.
[0124] Even when the additives contain a volatile compound or form
a thermal decomposition product by thermal decomposition, they can
be removed by evacuation at the same time.
[0125] The above additives may be added to and kneaded into the
aromatic polycarbonate or other polymer as a composition containing
them in high concentration (that is, master batch).
[0126] A general twin screw extruder has such a structure that a
full-flight unit having a spiral blade for forwarding aresin is
installed as a screw in the extruder to move a molten resin toward
an outlet by the rotation of the screw. When the components are
kneaded into the resin using such a twin screw extruder, a special
screw constituent unit such as a material seal unit, neutral
kneading unit or forward kneading unit must be installed as a part
of the module to improve a kneading effect.
[0127] However, when such a special screw constituent unit such as
a material seal unit, neutral kneading unit or forward kneading
unit is installed, the resin filling rate markedly rises in the
area of the constituent unit. When a full-flight unit is installed
next to and on a downstream side of the constituent unit, the resin
filling rate of a connection portion with the full-flight unit of
the constituent unit or the constituent unit itself changes
discontinuously. As a result, a dead space is formed at a site
where the resin filling rate changes discontinuously, thereby
causing residence deterioration such as the coloration,
crosslinking or gelation of the resin and increasing the content of
foreign matter in the resin.
[0128] The resin filling rate is determined by the throughput,
revolution speed and the constitution of agitation elements of the
twin screw extruder. A discontinuous change in the resin filling
rate frequently occurs when a full-flight unit is installed next to
and on a downstream side of a material seal unit, neutral kneading
unit or forward kneading unit.
[0129] According to the present invention, by using an extruder in
which a back kneading unit is installed at a position where the
resin filling rate of the twin screw extruder described above
changes discontinuously, the effect of eliminating a dead space can
be obtained and a resin which is free from residence deterioration
such as coloration, crosslinking or gelation and has an extremely
small content of foreign matter can be produced.
[0130] A description is subsequently given of main units arranged
in the twin screw extruder of the present invention.
[0131] As shown in FIG. 1(b), the back kneading unit used in the
present invention consists of back kneading segments which are
agitation elements constructed by combining together a plurality of
flat plates having basically a spindle shape when seen from a
transverse direction of the twin screw extruder.
[0132] It is preferred to combine together 2 or more, preferably 5
to 13 spindle-shaped flat plates.
[0133] The thickness of each of the spindle-shaped flat plates is
preferably 0.05 to 0.5 time the diameter of the screw. Further, the
ratio of the long axis to the short axis of the spindle shape is
1.1 to 2.0 and the maximum value of the long axis of the spindle
shape is preferably 0.950 to 0.995 time the diameter of the
cylinder body.
[0134] The spindle-shaped flat plates have the function of moving
the resin in a backward direction. By providing this function to
the spindle-shaped flat plates, the resin filling rate of the twin
screw extruder is reduced not discontinuously but continuously and
the effect of eliminating a dead space which is the effect of the
present invention is obtained. When the spindle-shaped flat plates
are outside the above ranges and the range of phase angle, their
function of moving the resin in a backward direction is lost or
unsatisfactory, whereby the resin filling rate of the twin screw
extruder is reduced discontinuously, thereby making it impossible
to eliminate a dead space, causing residence deterioration such as
the coloration, crosslinking or gelation of the resin and
increasing the content of foreign matter in the resin.
[0135] The seal ring unit (e) used in the present invention is
basically constructed by fitting one circular flat plate onto each
of left and right shafts but two or more flat plates may be fitted
according to application purpose.
[0136] The thickness in the direction of the screw shaft of the
circular flat plate is preferably 0.05 to 0.5 time the diameter of
the screw. Further, the diameter of the circular flat plate is
preferably 0.950 to 0.995 time the diameter of the cylinder
body.
[0137] The neutral kneading unit (d) used in the present invention
consists of neutral kneading segments constructed by combining
together 2 or more, preferably 5 to 13 spindle-shaped flat plates.
Since the spindle-shaped plates have a phase angle of 90.degree.,
they do not have the function of moving the resin.
[0138] The thickness in the direction of the screw shaft of each of
the spindle-shaped flat plates of the neutral kneading unit is
preferably 0.05 to 0.5 time the diameter of the screw. Further, the
ratio of the long axis to the short axis of the spindle shape is
1.1 to 2.0 and the maximum value of the long axis of the spindle
shape is preferably 0.950 to 0.995 time the diameter of the
cylinder body.
[0139] The forward kneading unit (c) used in the present invention
consists of forward kneading segments constructed by combining
together 2 or more, preferably 5 to 13 spindle-shaped flat plates
as well. The forward kneading unit has the function of moving the
resin in the traveling direction of the resin due to the existence
of a phase angle.
[0140] The thickness in the direction of the screw shaft of each of
the spindle-shaped flat plates of the forward kneading unit is
preferably 0.05 to 0.5 time the diameter of the screw. Further, the
ratio of the long axis to the short axis of the spindle shape is
1.1 to 2.0 and the maximum value of the long axis of the spindle
shape is preferably 0.950 to 0.995 time the diameter of the
cylinder body.
[0141] As described above, the twin screw extruder of the present
invention is aimed to add and knead the above components into the
molten aromatic polycarbonate and a module consisting of some units
having specific structures and functions is installed in the
extruder.
[0142] The module installed in the extruder of the present
invention has the function of causing the aromatic polycarbonate
(may be simply referred to as "resin" hereinafter) to flow in the
extruder while reducing the filling rate of the aromatic
polycarbonate little by little not discontinuously but continuously
and the function of eliminating a dead space from the extruder as
much as possible, thereby suppressing residence deterioration such
as the coloration, crosslinking or gelation of the resin and making
it possible to obtain a high-quality resin which has an extremely
small content of foreign matter.
[0143] In the present invention, the module has a supply port for
supplying the components, a kneading area for substantially
kneading the components and a vent area for discharging volatile
components derived from the components added to the kneading area
or contained in the resin from the extruder. The kneading area is
located on an upstream side and the vent area is located on a
downstream side.
[0144] One of the structural features of the module of the present
invention is that the back kneading unit is located on an upstream
side of the full-flight unit to prevent a discontinuous change
(reduction) in the filling rate in each section of the resin.
Typical one of the modules of the present invention (to be referred
to as "module A" hereinafter) consists of a kneading unit, a
material seal unit, a back kneading unit and a full-flight unit
which are arranged from an upstream side to a downstream side of a
flow of the resin.
[0145] Another typical module (to be referred to as "module B"
hereinafter) consists of a neutral kneading unit or forward
kneading unit, a back kneading unit and a full-flight unit which
are arranged from an upstream side to a downstream side of a flow
of the resin.
[0146] Still another module consists of a full-flight unit, a
material seal unit, a back kneading unit and a full-flight unit.
This module is preferably used, for example, when powdery
components are added using a side feeder right after the vent area
of the full-flight unit.
[0147] The twin screw extruder of the present invention comprises
at least 1, preferably 2 to 8 of the module A and the module B as
main constituent elements. To help the understanding of the present
invention, the structural diagram of the modules of the twin screw
extruder of the present invention is shown in FIG. 2. FIG. 2 shows
an extruder comprising two modules B and two modules A which are
arranged from an upstream side to a downstream side of a flow of
the resin. In FIG. 2, each module consists of 3 to 4 units and has
a supply port for adding components to be kneaded and a vent port
for discharging volatile components.
[0148] The number of modules and a combination of modules A and B
in FIG. 2 are just for explanation and optionally changed in an
actual process. The type of module is selected by the types and
quantities of the components to be kneaded. The number of modules
is at least 1, preferably 2 to 8, more preferably 3 to 7 from a
practical point of view.
[0149] The concrete structure of each module, the supply of
components to be kneaded and the discharge of volatile components
from the vent port will be described in detail hereinunder.
[0150] The module A in the present invention consists of a kneading
unit, a material seal unit, a back kneading unit and a full-flight
unit as described above. The kneading unit of the module A is an
area where the components to be kneaded are added to and kneaded
into the resin and selected from (b) a back kneading unit, (c) a
forward kneading unit and (d) a neutral kneading unit shown in FIG.
1 according to the propose of this kneading unit. They may be used
alone or in combination of two or three. The number of
spindle-shaped flat plates constituting each of the units of FIGS.
1(b), 1(c) and 1(d) is 4 to 5. FIG. 1 shows the smallest number of
spindle-shaped flat plates (segment). For example, the number of
flat plates for each unit is 2 to 13, preferably 5 to 7.
[0151] The material seal unit of the module A can be (e) a seal
ring unit or (g) a back flight unit but it is preferably (e) a seal
ring unit.
[0152] In the module A, a back kneading unit and a full-flight unit
are arranged on a downstream side of the material seal unit and a
continuous reduction in the resin filling rate can be realized by
combining these units. This full-flight unit has a vent port for
discharging volatile components.
[0153] As described above, the module B of the present invention
consists of a neutral kneading unit or forward kneading unit, a
back kneading unit and a full-flight unit. The first unit (the most
upstream side) of the module B is a neutral kneading unit or
forward kneading unit. In the area of this unit, the components to
be kneaded are added to and kneaded into the resin. The basic
configurations of these units are shown in FIGS. 1(c) and 1(d).
This first unit may be either one of a neutral kneading unit, a
forward kneading unit and a combination thereof.
[0154] In the module B, a back kneading unit and a full-flight unit
are arranged on a downstream side of the first unit and the
residence deterioration of the resin is greatly suppressed by a
combination of these units. The area of the full-flight unit on the
most downstream side has a vent port.
[0155] According to the present invention, there is provided a
method of adding and kneading components into an aromatic
polycarbonate using a twin screw extruder comprising the above
module A or B.
[0156] That is, according to the present invention, there is
provided a method of kneading components into an aromatic
polycarbonate using a twin screw extruder comprising at least one
module A consisting of a kneading unit, a material seal unit, a
back kneading unit and a full-flight unit which are arranged from
an upstream side to a downstream side, the method comprising the
steps of:
[0157] (1) supplying the components to the area of the kneading
unit of the module of the twin screw extruder; and
[0158] (2) discharging volatile components from the area of the
full-light unit of the module of the twin screw extruder as
required.
[0159] Further, according to the present invention, there is
provided a method of kneading components into an aromatic
polycarbonate using a twin screw extruder comprising at least one
module B consisting of a neutral kneading unit or forward kneading
unit, a back kneading unit and a full-flight unit which are
arranged from an upstream side to a downstream side, the method
comprising the steps of:
[0160] (1) supplying the components to the area of the neutral
kneading unit or the forward kneading unit of the module of the
twin screw extruder; and
[0161] (2) discharging volatile components from the area of the
full-light unit of the module of the twin screw extruder as
required.
[0162] These methods of the present invention are industrially
excellent as a method of adding and kneading components such as a
terminal OH group capping agent, catalyst deactivator,
devolatilizing agent and resin additives into an aromatic
polycarbonate.
[0163] To carry out the method of the present invention, there are
preferred modes of the supply conditions, supply means and kneading
conditions of the components or the discharge conditions of the
volatile components according to the addition purpose and types of
the components. These preferred modes will be described
hereinunder.
[0164] To knead the terminal OH group capping agent in accordance
with the method of the present invention so as to carry out the
terminal OH group capping reaction of the aromatic polycarbonate,
the terminal OH group capping agent is supplied from the supply
port of the kneading area of the module. As described above, the
kneading area is the kneading unit of the module A or the neutral
kneading unit or forward kneading unit of the module B. The module
B is advantageously used to knead the terminal OH group capping
agent.
[0165] Volatile components generated by the reaction of the
terminal OH group capping agent are discharged from the vent area
of the full-flight unit to the outside of the extruder by a vacuum
pump or the like.
[0166] The temperature at the time of kneading the terminal OH
group capping agent into the aromatic polycarbonate is 200 to
350.degree. C., preferably 240 to 320.degree. C. When the
temperature is lower than 200.degree. C., it is difficult to knead
the aromatic polycarbonate with the terminal OH group capping agent
and when the temperature is higher than 350.degree. C., the
terminal OH group capping agent itself volatilizes to the outside
of the extruder, thereby greatly reducing reactivity and causing
the thermal decomposition of the aromatic polycarbonate
disadvantageously.
[0167] The pressure of the kneading area is 1.013.times.10.sup.5 Pa
or less, preferably 6.667.times.10.sup.4 Pa or less. When the
pressure is higher than 1.013.times.10.sup.5 Pa, a by-product
produced by the terminal OH group capping reaction cannot be
removed from the extruder immediately and the decomposition of the
aromatic polycarbonate occurs disadvantageously.
[0168] The time for kneading the aromatic polycarbonate with the
terminal OH group capping agent is determined by the average
residence time of the aromatic polycarbonate in the kneading area.
In the case of an extruder having a plurality of kneading areas,
the kneading time is expressed by the total of the kneading times
of the plurality of kneading areas, generally 0.05 second or more,
preferably 0.1 to 1,000 seconds. When the kneading time is shorter
than 0.05 second, it is difficult to knead the aromatic
polycarbonate with the terminal OH group capping agent and the
terminal OH group capping reaction does not proceed.
[0169] The pressure of the vent area after the addition and
kneading of the terminal OH group capping agent is
1.013.times.10.sup.5 Pa or less, preferably 6.667.times.10.sup.4 Pa
or less. When the pressure of the vent area is higher than
1.013.times.10.sup.5 Pa, the produced by-product cannot be removed
from the extruder and the decomposition of the aromatic
polycarbonate occurs disadvantageously.
[0170] The evacuation time of the vent area is determined by the
average residence time of the aromatic polycarbonate in the vent
area. In the case of an extruder having a plurality of vent areas,
the evacuation time is expressed by the total of the evacuation
times of the plurality of vent areas, preferably 0.05 second or
more, particularly preferably 0.1 to 500 seconds. When the
evacuation time is shorter than 0.05 second, the produced
by-product cannot be removed from the extruder, the decomposition
of the aromatic polycarbonate occurs, and the reaction by-product
remains in the aromatic polycarbonate and reduces the quality of a
final product.
[0171] When a plurality of modules are arranged in the extruder
used, the terminal OH group capping agent can be divided into
portions corresponding to the number of the modules and supplied to
the modules.
[0172] According to the present invention, by employing preferred
ranges of the above temperature and pressure of the kneading area,
kneading time, the pressure and evacuation time of the vent area,
and the sort and quantity of the terminal OH group capping agent,
the decomposition of the aromatic polycarbonate caused by the
reaction by-product can be suppressed, it is made easy to control
the intrinsic viscosity of the finally produced aromatic
polycarbonate, a terminal OH group capping reaction can be
completed quickly, and an aromatic polycarbonate whose terminal is
capped and which has an extremely small content of foreign matter
can be produced.
[0173] Even when a catalyst deactivator is to be kneaded in
accordance with the method of the present invention, the catalyst
deactivator is supplied to the extruder from the kneading area of
the module A or B. When a plurality of modules are arranged in the
extruder, the catalyst deactivator can be divided into portions
corresponding to the number of the modules and supplied to the
modules. The catalyst deactivator may be kneaded into the aromatic
polycarbonate directly or after it is formed into master pellets or
dissolved or dispersed in an appropriate solvent.
[0174] The kneading of the catalyst deactivator is preferably
carried out by using the module A and supplying the catalyst
deactivator to the kneading unit of the module A.
[0175] The aromatic polycarbonate is kneaded with the catalyst
deactivator at a temperature of 200 to 350.degree. C., preferably
240 to 320.degree. C. for 0.05 second or more, preferably 0.1 to
100 seconds. When the temperature is lower than 200.degree. C., it
is difficult to knead the aromatic polycarbonate with the catalyst
deactivator and when the temperature is higher than 350.degree. C.,
the thermal decomposition of the aromatic polycarbonate occurs
disadvantageously.
[0176] When the catalyst deactivator is added as a solution, a
solvent used in the solution serves as a devolatilizing agent to
improve the effect of removing volatile components.
[0177] The vent area of the full-flight unit is evacuated by a
vacuum pump or the like to remove the solvent and the volatile
components from the extruder. The evacuation is carried out at a
pressure of 1.013.times.10.sup.5 Pa or less, preferably
6.667.times.10.sup.4 Pa or less for 0.05 second or more, preferably
0.1 to 500 seconds. When the pressure of the vent area is higher
than 1.013.times.10.sup.5 Pa, the added solvent and the volatile
components cannot be removed from the extruder.
[0178] The aromatic polycarbonate, which is produced by the melt
method, obtained by kneading the catalyst deactivator in accordance
with the present invention loses the activity of the residual
catalyst and can be molded into a molded product having excellent
stability.
[0179] The devolatilizing agent has the function of promoting the
removal of volatile components such as an aromatic monohydroxy
compound (such as phenol) by-produced in the production of the
aromatic polycarbonate, raw materials (aromatic diol and carbonic
acid diester) and a low molecular weight oligomer by vaporization
under reduced pressure. When various components are kneaded, the
devolatilizing agent has the function of removing volatile
components generated from the used solvent or a kneading
reaction.
[0180] The devolatilizing agent is supplied from the kneading area
of the module A or B. That is, it is supplied from the kneading
unit in the case of the module A and from the neutral kneading unit
or forward kneading unit in the case of the module B. The
devolatilizing agent may be divided into portions corresponding to
the number of modules and supplied to the modules, which is more
preferred than a case where the devolatilizing agent is kneaded at
a time. The devolatilizing agent is preferably kneaded using the
module A.
[0181] The devolatilizing agent is discharged from the vent port of
the full-flight unit of the module under reduced pressure.
[0182] The aromatic polycarbonate is kneaded with the
devolatilizing agent at a temperature of 200 to 350.degree. C.,
preferably 240 to 320.degree. C. and a pressure of 0.3 MPa or more,
preferably 0.5 MPa or more. When the temperature is lower than
200.degree. C., it is difficult to knead the aromatic polycarbonate
with the devolatilizing agent and when the temperature is higher
than 350.degree. C., the thermal decomposition of the aromatic
polycarbonate occurs disadvantageously.
[0183] In the present invention, the time for kneading the aromatic
polycarbonate in the presence of the devolatilizing agent is
determined by the average residence time of the aromatic
polycarbonate in the kneading area. In the case of an extruder
having a plurality of kneading areas, the time is expressed by the
total of the average residence times of the plurality of kneading
areas but preferably 0.05 to 100 seconds, particularly preferably
0.1 to 60 seconds. When the kneading time in the presence of the
devolatilizing agent is below the above range, the removal of
volatile components may be unsatisfactory and when the kneading
time is above the range, it is economically disadvantageous.
[0184] The devolatilizing agent is discharged from the vent area of
the full-flight unit of the module to the outside of the extruder
by a vacuum pump together with the volatile components under
reduced pressure. The pressure at this point is
1.013.times.10.sup.5 Pa or less, preferably 6.667.times.10.sup.4 Pa
or less and the time is 0.05 second or more, preferably 0.1 to 500
seconds.
[0185] The resin additives may be kneaded into the aromatic
polycarbonate directly or after they are formed into master pellets
or dissolved or dispersed in an appropriate solvent. The resin
additives are supplied to the kneading area of the kneading unit of
the module A or B. It is preferred to supply the resin additives to
the kneading area of the kneading unit of the module A. The resin
additives may be each divided into portions and supplied from a
plurality of modules, or the resin additives may be divided into
groups and supplied from a plurality of modules separately.
[0186] The aromatic polycarbonate is kneaded with the resin
additives at a temperature of 200 to 350.degree. C., preferably 240
to 320.degree. C. and a pressure of 0.3 MPa or more, preferably 0.5
MPa or more for 0.05 second or more, preferably 0.1 to 1,000
seconds. When the temperature is lower than 200.degree. C., it is
difficult to knead the aromatic polycarbonate with the resin
additives and when the temperature is higher than 350.degree. C.,
the thermal decomposition of the aromatic polycarbonate occurs
disadvantageously.
[0187] The vent area of the full-flight unit of the module is
preferably evacuated by a vacuum pump or the like to remove the
solvent and volatile components from the extruder. The evacuation
is carried out at a pressure of 1.013.times.10.sup.5 Pa or less,
preferably 6.667.times.10.sup.4 Pa or less for 0.05 second or more,
preferably 0.1 to 500 seconds. When the pressure of the vent area
is higher than 1.013.times.10.sup.5 Pa, the added solvent and the
volatile components cannot be removed from the extruder.
[0188] Preferred modes of the method and conditions of kneading the
components have been described. Each of the components may be
kneaded independently, or mixtures of two or three of the
components may be kneaded into the aromatic polycarbonate.
[0189] The inventors of the present invention have found that an
aromatic polycarbonate having an extremely small content of
volatile components is obtained unexpectedly by simple operation
when water as a devolatilizing agent is kneaded into an aromatic
polycarbonate using the twin screw extruder comprising a module(s)
of the present invention under specific conditions and volatile
components are discharged from the vent area.
[0190] The present inventors have also found that the content of
volatile components contained in the aromatic polycarbonate can be
significantly reduced and the effect of adding a catalyst
deactivator can be further improved by supplying the catalyst
deactivator together with water when water is kneaded under
specific conditions in the above method and that the addition and
kneading of water and the catalyst deactivator can be carried out
in the same module.
[0191] According to the present invention, there is provided a
method of removing volatile components from an aromatic
polycarbonate as an improved method comprising the steps of
kneading water into the aromatic polycarbonate at an absolute
pressure of 0.3 to 10 MPa in the kneading area of the kneading unit
of the module of a twin screw extruder comprising at least one
module of the present invention and discharging and removing
volatile components from the area of the full-flight unit of the
module.
[0192] According to the present invention, there is also provided a
method of kneading a mixed solution of water and a catalyst
deactivator in place of water in the above method at an absolute
pressure of 0.3 to 10 MPa as a further improved method.
[0193] A detailed description is subsequently given of these
methods.
[0194] These methods are a high-pressure water kneading method and
characterized in that units on an upstream side and on a downstream
side of the module are operated with a very large pressure
difference between them because volatile components including water
are discharged under reduced pressure from the full-flight unit
arranged on a downstream side through the material seal unit and
the back kneading unit.
[0195] It is assumed that the devolatilizing agent dispersed in the
polymer uniformly in the kneading unit swells abruptly in the
full-flight unit due to this large pressure difference and, result
of it, the surface area of the polymer through which the volatile
components contained in the polymer are evaporated is increased
significantly, thereby promoting the removal of the volatile
components.
[0196] Therefore, the use of the module A is advantageous for this
high-pressure kneading method, a continuous reduction in the
filling rate of the aromatic polycarbonate can be realized from the
material seal unit to the full-flight unit regardless of the large
pressure difference, and the generation of foreign matter can be
suppressed.
[0197] In the above method, water is kneaded at an absolute
pressure of 0.3 to 10 MPa, preferably 0.5 to 5 MPa, particularly
preferably 1 to 2 MPa and a temperature of 200 to 350.degree. C.,
preferably 220 to 300.degree. C. The kneading time is 0.05 to 20
seconds, preferably 0.1 to 15 seconds per module. When a plurality
of modules are used, the total kneading time is 0.05 to 100
seconds, preferably 0.1 to 60 seconds.
[0198] The proportion of water kneaded is 0.1 to 5 parts by weight,
preferably 0.3 to 4 parts by weight based on 100 parts by weight of
the aromatic polycarbonate per module.
[0199] Further, in the above method, a mixed solution of water and
a catalyst deactivator can be kneaded directly without deactivating
a catalyst in advance, and the deactivation of the catalyst and the
removal of volatile components can be carried out in the same
module.
[0200] In this case, it has been found that the decomposition of
the polymer caused by water does not occur substantially because
the deactivation of the catalyst takes place very quickly.
[0201] When a mixed solution of water and a catalyst deactivator is
kneaded in this method, the pressure, temperature and kneading time
are substantially the same as above. The proportion of water is
also the same as above. The proportion of the catalyst deactivator
contained in the mixed solution is 0.5 to 50 equivalent, preferably
0.5 to 10 equivalent, particularly preferably 0.8 to 5 equivalent
based on 1 equivalent of a polymerization catalyst contained in the
aromatic polycarbonate.
[0202] Under the above conditions, water or a mixed solution of
water and a catalyst deactivator is supplied to the kneading area
of the kneading unit of the module at a high pressure and kneaded
into the aromatic polycarbonate, and volatile components including
water are discharged from the vent area of the full-flight unit of
the module to the outside of the extruder under reduced pressure.
In this case, the pressure of the vent area is 1.333.times.10 Pa
(0.1 mmHg) to 1.013.times.10.sup.5 Pa (760 mmHg), preferably
1.333.times.10.sup.2 Pa (1 mmHg) to 6.667.times.10.sup.4 Pa (500
mmHg).
[0203] The volatile components (especially raw material components,
reaction by-product, solvent and the like) contained in the
aromatic polycarbonate can be removed very effectively by the above
improved method, and an aromatic polycarbonate which is excellent
in thermal stability, color stability and hydrolysis resistance and
has an extremely small content of these components can be obtained.
Further, when the aromatic polycarbonate is kneaded with a catalyst
deactivator together with water, a catalyst deactivating effect is
improved together with the above effect and such an effect that the
kneading step can be simplified can also be obtained.
[0204] When water is used as a devolatilizing agent in the present
invention, water is discharged from the vent area of each module of
the extruder to the outside of the extruder as water vapor by a
vacuum pump together with the volatile components.
[0205] As means of collecting and separating the volatile
components from water vapor containing the volatile components (low
molecular weight substances) under reduced pressure, the following
methods have been employed heretofore: one in which a plurality of
heat exchangers or tanks having a cooling jacket and/or coil are
used to cool low molecular weight substances to a temperature below
their melting points under vacuum, condense them on the heat
exchanging surface and collect them, a spare device is switched on
when a pressure difference between inlet and outlet sides of the
apparatus is caused by the adhesion of the low molecular weight
substances, and washing by heating or with a solvent is carried out
to remove the low molecular weight substances, and one in which a
solvent which can dissolve generated low molecular weight
substances is used as a scrubbing solution and contacted to the
vapor of the low molecular weight substances to dissolve and
collect the low molecular weight substances.
[0206] However, since the above methods which have been
conventionally used require the switching and washing of the
apparatus, complex equipment is required or a large amount of the
solvent must be regenerated by distillation for the recycling of
the scrubbing solution. Therefore, the above methods have such a
problem that a great cost is required to collect low molecular
weight substances under reduced pressure continuously and
stably.
[0207] According to studies conducted by the present inventors,
there has been found an inexpensive collection method which enables
the operation of collecting low molecular weight substances under
reduced pressure to be carried out easily and continuously.
[0208] That is, according to the present invention, there is
provided a method of removing volatile components contained in an
aromatic polycarbonate using a twin screw extruder and water as a
devolatilizing agent, characterized in that a vacuum collection
system comprising the following steps is installed between the vent
port of the extruder and a vacuum pump:
[0209] 1) the step of condensing water vapor and volatile
components by introducing these vapor generated in the extruder
into a scrubber which uses cool water as a scrubbing solution and
contacting them to the cool water having a temperature below its
boiling point at the operation pressure of the scrubber;
[0210] 2) the step of separating solidified volatile components
from the scrubbing solution containing the solidified volatile
components discharged from the scrubber;
[0211] 3) the step of cooling water from which the solidified
volatile components have been separated to a temperature below its
boiling point at the operation pressure of the scrubber; and
[0212] 4) the step of circulating the cooled water to the
scrubber.
[0213] In the above removing method, water as a devolatilizing
agent to be kneaded in the extruder may contain not only water but
also other components to be kneaded as described above, especially
a mixed solution of a catalyst deactivator and water may be
used.
[0214] As described above, when water is used as a component to be
kneaded in the kneading method of the present invention, water is
discharged from the vent area of the full-flight unit of each
module to the outside of the extruder as water vapor by a vacuum
pump under reduced pressure together with the volatile
components.
[0215] The removing method of the present invention is a system for
collecting volatile components from water vapor discharged from the
full-flight unit of the extruder. This collection system will be
described with reference to FIGS. 3 to 6 but it should be
understood that the present invention is not limited by these
figures.
[0216] The "vacuum pump" as used herein means a device for
generating vacuum. Besides the vacuum pump shown in FIG. 3, an
ejector or the like may also be used.
[0217] The expression "between a vapor line 9 and a vacuum pump 1"
refers to between a vacuum line 2 for connecting the vent of a twin
screw extruder 21 and a vapor line 9 for connecting the vacuum pump
1 shown in FIG. 3.
[0218] A scrubber 10 is arranged between the vacuum line 2 for
connecting the vent of the twin screw extruder 21 and the vapor
line 9 for connecting the vacuum pump 1.
[0219] A scrubber used in the present invention is not particularly
limited and any structured scrubber may be used if it can contact
the scrubbing solution to vapor well and has a small pressure loss.
An example of the scrubber is shown in FIG. 4.
[0220] In FIG. 4, reference numeral 10 denotes a cylindrical
vertical column (scrubber body) installed upright, a plurality of
spray nozzles 3 are installed in a center portion in a sectional
direction of the column 10 at different heights, and a required
amount of the scrubbing solution is sprayed from the spray nozzles
3.
[0221] An inlet 5 for introducing gas containing water vapor
discharged from the twin screw extruder is provided on the side
wall of the column 10 so that the vapor of volatile components
introduced into the column from the inlet 5 is contacted to the
scrubbing solution to be solidified by cooling and removed.
[0222] The vapor of water used as a devolatilizing agent is
liquefied and contained in the scrubbing solution. Gas from which
water vapor and the vapor of the volatile components have been
removed is introduced into the vacuum pump 1 from an outlet 4 for
the vacuum line provided at the top of the column 10 and
discharged.
[0223] Care must be taken to protect the inlet 5 from spray of the
scrubbing solution.
[0224] The scrubbing solution containing the collected solidified
volatile components, water used as a devolatilizing agent and
water-soluble volatile components is discharged from an outlet 6
provided at a lower portion of the column.
[0225] In the removing method of the present invention, since the
scrubbing solution contains water as a devolatilizing agent, the
scrubbing solution discharged from the scrubber becomes a water
slurry containing the collected solid volatile components. The
slurry is introduced into a scrubbing solution storage tank 7
through a scrubbing solution line 11.
[0226] The scrubbing solution storage tank 7 is preferably equipped
with an agitator to prevent the sedimentation of the slurry.
[0227] When the above scrubber is used, the spray nozzle used is
preferably a full cone nozzle having sprayed liquid drops inside a
spray cone as shown in FIG. 5 or a hollow cone nozzle whose inside
is hollow as shown in FIG. 6. Out of these, the full cone nozzle is
the most preferred.
[0228] The flow rate of the scrubbing solution is preferably 100 to
1,000 times the total weight of water vapor and the gases of
volatile components discharged from the twin screw extruder.
[0229] The temperature of water used as the scrubbing solution must
be controlled to a temperature below its boiling point at the
collection pressure of the scrubber. When the temperature is higher
than the boiling point, it is difficult to maintain a degree of
vacuum required for evacuation due to the vaporization of the
scrubbing solution and the volatile components distill out into the
vacuum pump disadvantageously. The temperature is desirably
controlled to a temperature 5.degree. C. lower than the boiling
point of water at the collection pressure from the view point of
collection efficiency.
[0230] It is desirable to always maintain the vapor line 9 for
connecting the twin screw extruder 21 to the spray nozzle 3 and the
inlet 5 for the vapor line provided in the scrubber shown in FIG. 3
at a temperature of 100.degree. C. or more by a heating medium such
as steam or a heating unit such as a jacket to prevent the adhesion
of volatile components (low molecular weight substances).
[0231] The installation angle 8 of the inlet 5 shown in FIG. 4 for
introducing vapor into the scrubber is preferably 45 to 80.degree.
from a vertical direction so that the nozzle descends toward the
scrubber.
[0232] When low molecular weight substances adhere to the inner
wall of the scrubber column, a spray nozzle for cleaning the
adhered portions may be provided to forcedly clean with spray.
[0233] In the scrubber and the scrubbing solution line 11 shown in
FIG. 3 for connecting the scrubber to the scrubbing solution
storage tank, it is desirable not to make a portion having a
diameter which greatly differs from that of other portion because
it becomes resistance against a flow of the scrubbing solution
containing discharged solid volatile components. When such a
portion is made, the restriction angle is preferably set to
10.degree. or less.
[0234] As shown in FIG. 4, the scrubbing solution containing the
collected solids in the scrubbing solution storage tank 7 is
introduced into a separator 14 for removing the collected solids
contained in the scrubbing solution by a scrubbing solution pump
13.
[0235] A method of separating solidified volatile components is not
particularly limited and any methods are acceptable if they can
remove solids contained in the scrubbing solution efficiently and
thoroughly. Out of these, a method which separates solids by
centrifugation or filtration is preferred.
[0236] An apparatus for separating solids by centrifugation is not
particularly limited and centrifugal separators available on the
market may be used, as exemplified by horizontal continuous
centrifugal separators and semi-continuous centrifugal separators
having a vertical inner screen.
[0237] An apparatus for separating solids by filtration is not
particularly limited but continuous filters such as a belt filter
and drum filter, cartridge filters, basket type filters, strainers
and the like may be used. These devices may be used in combination
as required.
[0238] As for the collection accuracy of solids contained in the
scrubbing solution, the mesh of the filter is 10 .mu.m or less.
That is, 90% or more of particles of 10 .mu.m in diameter are
preferably collected, and 90% or more of particles of 2 .mu.m in
diameter are more preferably collected. When a device which cannot
carry out solid-liquid separation thoroughly is used, undissolved
solids are adhered to the inner surface of a scrubbing solution
line 16 and the inside of other devices, thereby preventing
long-time continuous operation.
[0239] It is preferred to set the flow rates of scrubbing solution
lines 12 and 15 between the scrubbing solution storage tank and the
solid-liquid separator to 1 m/s or more so as to prevent the
adhesion of solids to the inner surfaces of the lines and to
eliminate the resistance (part) such as an unneeded curved portion
on the like as much as possible so as to reduce the flow
resistance.
[0240] After the above solid-liquid separator, it is preferred to
discharge a surplus of water from the collection system and to
treat a waste water treatment as required in order to suppress an
increase in the amount of the scrubbing solution caused by water
used as a devolatilizing agent.
[0241] To recycle water from which solidified volatile components
have been removed as the scrubbing solution, the water is cooled to
a predetermined temperature below its boiling point at the
operation pressure of the scrubber by a scrubbing solution cooler
18. A device used for this purpose is not particularly limited and
a cooling jacket and/or coil is installed in the above scrubbing
solution storage tank 7 having a stirrer, or a heat exchanger such
as a multi-tube heat exchanger, plate type heat exchanger or
scraping type heat exchanger may be used.
[0242] A device for circulating cooled water to the scrubber is a
line for connecting the above solution cooler 18 and the spray
nozzle of the scrubber consisting of a flow meter 19 and a
scrubbing solution line equipped with an automatic valve for the
control of flow rate. An undesired curved portion is eliminated as
much as possible to prevent pressure resistance in the scrubbing
solution line 16.
[0243] Not only smooth continuous long-time operation is made
possible but also labor and energy required during operation can be
greatly reduced by the vapor collecting method of the present
invention.
[0244] Since water which is a devolatilizing agent is used as the
scrubbing solution, compared with a case where other organic
solvent or the like is used as a scrubbing solution, the process of
collecting a devolatilizing agent can be greatly simplified and
recycling can be carried out with ease because volatile components
collected by a filter or the like are not subjected to a heat
treatment or solvent treatment.
[0245] The present invention is applied to an aromatic
polycarbonate. However, the present invention can also be applied
to other resin which may suffer residence deterioration such as
coloration, crosslinking or gelation. The effect of the present
invention is large for commonly used thermoplastic resins,
particularly polyethylene, polystyrene, polyvinyl chloride,
polyamides and polyesters which readily suffer residence
deterioration such as coloration, crosslinking or gelation.
However, out of these, aromatic polycarbonates are very sensitive
to residence deterioration such as coloration, crosslinking or
gelation and the utility values of the apparatus and method of the
present invention are particularly large.
EXAMPLES
[0246] Examples of the present invention are given below. These
examples are provided for the purpose of further illustrating the
present invention but are in no way to be taken as limiting.
[0247] "%" and "parts" in the examples mean "% by weight" and
"parts by weight", respectively, unless otherwise stated. The
physical properties of aromatic polycarbonates obtained in the
following examples were measured as follows.
[0248] (1) Intrinsic Viscosity and Viscosity Average Molecular
Weight
[0249] The intrinsic viscosity of a methylene chloride solution
having a concentration of 0.7 g/dl was measured using an Ubbellohde
viscometer and the viscosity average molecular weight was obtained
from the following equation.
[.eta.]=1.23.times.10.sup.-4 M.sup.0.83
[0250] (2) Number of Foreign Substances
[0251] 100 g of a polycarbonate was dissolved in 1 liter of a
methylene chloride solution, the resulting solution was filtered
with the filter which has 30 .mu.m diameter's poses, and the number
of foreign substances remaining on the filter was counted through a
microscope.
[0252] (3) Amount of Volatile Components
[0253] Phenol and diphenyl carbonate contained in a solution of 100
g of a polycarbonate dissolved in 1 liter of methylene chloride
were extracted with acetonitrile and determined by the high-speed
liquid chromatography of Toso Co., Ltd.
[0254] (4) Pellet Color
[0255] Measured with the color difference meter of Nippon Denshoku
Kogyo Co., Ltd.
EXAMPLE 1
[0256] 2,2-bis(4-hydroxyphenyl)propane and diphenyl carbonate were
charged into a dissolution tank equipped with a stirrer in a molar
ratio of 1:1.02 and dissolved at 150.degree. C. after the inside of
the tank was substituted by nitrogen, and the mixed solution was
transferred to a raw material storage tank maintained at
150.degree. C.
[0257] Thereafter, the mixed solution was supplied continuously to
a vertical agitation tank equipped with a fractionating column and
maintained at an inner temperature of 220.degree. C. and an inner
pressure of 13,333 Pa (100 mmHg), a disodium salt of bisphenol A
and tetramethyl ammonium hydroxide were added continuously in
amounts of 5.times.10.sup.-7 equivalent and 1.times.10.sup.-4
equivalent based on 1 mol of 2,2-bis(4-hydroxyphenyl)propane,
respectively, and a reaction was carried out by removing the formed
phenol from the fractionating column. The obtained reaction product
(1) was discharged continuously using a gear pump.
[0258] The reaction product (1) was supplied continuously to a
vertical agitation tank equipped with a fractionating column
maintained at an inner temperature of 250.degree. C. and an inner
pressure of 1,333 Pa (10 mmHg). A reaction was carried out by
removing the formed phenol from a fractionating column. The
obtained reaction product (2) was discharged continuously using a
gear pump.
[0259] The reaction product (2) was then supplied continuously to a
horizontal reactor maintained at an inner temperature of
270.degree. C. and an inner pressure of 133 Pa (1 mmHg). An
aromatic polycarbonate having a viscosity average molecular weight
of 15,300 was obtained continuously by further carrying out
polymerization while the formed phenol was removed from the
reaction system.
[0260] The aromatic polycarbonate was then supplied continuously to
an intermeshing twin screw extruder. In the twin screw extruder, a
catalyst deactivator (tetrabutyl phosphonium salt of
dodecylbenzenesulfonic acid) was added and kneaded in a equivalent
amount 2 times that of a disodium salt of bisphenol A used as a
polymerization catalyst to deactivate the polymerization catalyst
and a devolatilizing agent (water) was added in an amount of 1 wt%
based on the polycarbonate to remove volatile components so as to
obtain a stabilized aromatic polycarbonate continuously. The
aromatic polycarbonate in a molten state was extruded from a dice
and pelletized by a pelletizer to obtain an aromatic polycarbonate
as a final product.
[0261] The addition and kneading of the catalyst deactivator and
the removal of volatile components were both carried out using a
module (A) consisting of a forward kneading unit, a neutral
kneading unit, a back kneading unit, a seal ring unit, a back
kneading unit and a full-flight unit which were arranged from an
upstream side, and the above additives were supplied to the forward
kneading unit.
[0262] The forward kneading unit used was constructed by combining
together 5 or more spindle-shaped flat plates, and the thickness in
a screw shaft direction of each of the spindle-shaped flat plates
was 0.1 time the diameter of the screw. Further, the ratio of the
long axis to the short axis of the spindle shape was 1.614, and the
maximum value of the long axis of the spindle shape was 0.979 time
the diameter of the cylinder body. The spindle-shaped flat plates
were combined together in a traveling direction of the aromatic
polycarbonate at a phase angle of 45.degree. in a positive
direction when the rotation direction of the shaft was
positive.
[0263] The neutral kneading unit used was constructed by combining
together 5 or more spindle-shaped flat plates, and the thickness in
a screw shaft direction of each of the spindle-shaped flat plates
was 0.1 time the diameter of the screw. Further, the ratio of the
long axis to the short axis of the spindle shape was 1.614, and the
maximum value of the long axis of the spindle shape was 0.979 time
the diameter of the cylinder body.
[0264] The back kneading unit used was constructed by combining
together 5 or more spindle-shaped flat plates, and the thickness in
a screw shaft direction of each of the spindle-shaped flat plates
was 0.1 time the diameter of the screw. Further, the ratio of the
long axis to the short axis of the spindle shape was 1.614, and the
maximum value of the long axis of the spindle shape was 0.979 time
the diameter of the cylinder body. The spindle-shaped flat plates
were combined together in a traveling direction of the aromatic
polycarbonate at a phase angle of 45.degree. in a negative
direction when the rotation direction of the shaft was
positive.
[0265] The seal ring unit used was constructed by fitting one
circular flat plate onto each of the right and left shafts, and the
thickness in a screw shaft direction of the circular flat plate was
0.1 time the diameter of the screw. The diameter of the circular
flat plate was 0.979 time the diameter of the cylinder body.
[0266] When the screw shaft was observed with the naked eye after
40 days of operation, it retained metallic luster before operation
and the adhesion of foreign matter such as a carbonized material
was not seen. Further, the maximum number of foreign substances
contained in the aromatic polycarbonate as a final product was 41
during operation.
EXAMPLE 2
[0267] The addition and kneading of a terminal OH group capping
agent (2-methoxycarbonyl phenyl phenyl carbonate) and a catalyst
deactivator (tetrabutyl phosphonium salt of dodecylbenzenesulfonic
acid) were carried out in the twin screw extruder. An aromatic
polycarbonate was obtained in the same manner as in Example 1
except that a module (B) used to add and knead the terminal OH
group capping agent consisted of a neutral kneading unit, a back
kneading unit and a full-flight unit which were arranged from an
upstream side and a module (A) used to add and knead the catalyst
deactivator consisted of a forward kneading unit, a back kneading
unit, a back flight unit, a back kneading unit and a full-flight
unit which were arranged from an upstream side.
[0268] When the screw shaft was observed with the naked eye after
40 days of operation, it retained metallic luster before operation
and the adhesion of foreign matter such as a carbonized material
was not seen. Further, the maximum number of foreign substances
contained in the aromatic polycarbonate as a final product was 39
during operation.
EXAMPLE 3
[0269] The addition and kneading of a terminal OH group capping
agent (2-methoxycarbonyl phenyl phenyl carbonate) and a catalyst
deactivator (tetrabutyl phosphonium salt of dodecylbenzenesulfonic
acid) were carried out in the twin screw extruder. An aromatic
polycarbonate was obtained in the same manner as in Example 1
except that a module (B) used to add and knead the terminal OH
group capping agent consisted of a forward kneading unit, a back
kneading unit and a full-flight unit which were arranged from an
upstream side and a module (A) used to add and knead the catalyst
deactivator consisted of a forward kneading unit, a back kneading
unit, a back flight unit, a back kneading unit and a full-flight
unit which were arranged from an upstream side.
[0270] When the screw shaft was observed with the naked eye after
40 days of operation, it retained metallic luster before operation
and the adhesion of foreign matter such as a carbonized material
was not seen. Further, the maximum number of foreign substances
contained in the aromatic polycarbonate as a final product was 44
during operation.
EXAMPLE 4
[0271] The addition and kneading of a catalyst deactivator
(tetrabutyl phosphonium salt of dodecylbenzenesulfonic acid) and an
additive (glycerin monostearate) were carried out in the twin screw
extruder. An aromatic polycarbonate was obtained in the same manner
as in Example 1 except that a module (A) used to add and knead the
catalyst deactivator consisted of a forward kneading unit, a back
kneading unit, a seal ring unit, a back kneading unit and a
full-flight unit which were arranged from an upstream side and a
module (B) used to add and knead the additive consisted of a
forward kneading unit, a back kneading unit and a full-flight unit
which were arranged from an upstream side.
[0272] When the screw shaft was observed with the naked eye after
40 days of operation, it retained metallic luster before operation
and the adhesion of foreign matter such as a carbonized material
was not seen. Further, the maximum number of foreign substances
contained in the aromatic polycarbonate as a final product was 41
during operation.
EXAMPLE 5
[0273] The addition and kneading of a catalyst deactivator
(tetrabutyl phosphonium salt of dodecylbenzenesulfonic acid) and
the addition and kneading of an additive master powder
(4,4'-biphenylenediphosphinic acid(2,4-di-t-butylphenyl)) with the
aid of a side feeder were carried out in the twin screw extruder. A
module (A) used to add and knead the catalyst deactivator consisted
of a forward kneading unit, a back kneading unit, a seal ring unit,
a back kneading unit and a full-flight unit which were arranged
from an upstream side, a module (C) used to add and knead the
additive master powder consisted of a full-flight unit, a back
flight unit, a back kneading unit and a full-flight unit which were
arranged from an upstream side, and a kneading and vent zone
consisting of a forward kneading unit, a neutral kneading unit, a
back kneading unit and a full-flight unit was provided after the
module (C). An aromatic polycarbonate was obtained in the same
manner as in Example 1 except that the additive master powder was
added to the second full-flight unit of the module (C).
[0274] When the screw shaft was observed with the naked eye after
40 days of operation, it retained metallic luster before operation
and the adhesion of foreign matter such as a carbonized material
was not seen. Further, the maximum number of foreign substances
contained in the aromatic polycarbonate as a final product was 39
during operation.
Comparative Example 1
[0275] The addition and kneading of a catalyst deactivator
(tetrabutyl phosphonium salt of dodecylbenzenesulfonic acid) and a
devolatilizing agent (water) were carried out in the twin screw
extruder. An aromatic polycarbonate was obtained in the same manner
as in Example 1 except that a module used to add and knead the
catalyst deactivator and the devolatilizing agent (water) consisted
of a forward kneading unit, a neutral kneading unit, a back
kneading unit, a seal ring unit and a full-flight unit which were
arranged from an upstream side.
[0276] When the screw shaft was observed with the naked eye after
40 days of operation, the adhesion of a carbonized material was
seen in the boundary between the seal ring unit and the full-flight
unit on a downstream side. Further, the maximum number of foreign
substances contained in the aromatic polycarbonate as a final
product was 100 or more during operation.
Comparative Example 2
[0277] The addition and kneading of a terminal OH group capping
agent (2-methoxycarbonyl phenyl phenyl carbonate) and a catalyst
deactivator (tetrabutyl phosphonium salt of dodecylbenzenesulfonic
acid) were carried out in the twin screw extruder. An aromatic
polycarbonate was obtained in the same manner as in Example 1
except that a module used to add and knead the terminal OH group
capping agent consisted of a neutral kneading unit and a
full-flight unit which were arranged from an upstream side and a
module used to add and knead the catalyst deactivator consisted of
a forward kneading unit, a back kneading unit, a back flight unit
and a full-flight unit which were arranged from an upstream
side.
[0278] When the screw shaft was observed with the naked eye after
40 days of operation, the adhesion of a carbonized material was
seen in the boundary between the surface of the neutral kneading
unit of the kneading area of the terminal OH group capping agent
and the full-flight unit on a downstream side. The adhesion of a
carbonized material was also seen in the boundary between the back
flight unit of the addition and kneading area of the catalyst
deactivator and the full-flight unit on a downstream side. Further,
the maximum number of foreign substances contained in the aromatic
polycarbonate as a final product was 100 or more during
operation.
Comparative Example 3
[0279] The addition and kneading of a terminal OH group capping
agent (2-methoxycarbonyl phenyl phenyl carbonate) and a catalyst
deactivator (tetrabutyl phosphonium salt of dodecylbenzenesulfonic
acid) were carried out in the twin screw extruder. An aromatic
polycarbonate was obtained in the same manner as in Example 1
except that a module used to add and knead the terminal OH group
capping agent consisted of a forward kneading unit and a
full-flight unit which were arranged from an upstream side and a
module used to add and knead the catalyst deactivator consisted of
a forward kneading unit, a back kneading unit, a back flight unit
and a full-flight unit which were arranged from an upstream
side.
[0280] When the screw shaft was observed with the naked eye after
40 days of operation, the adhesion of a carbonized material was
seen in the boundary between the surface of the forward kneading
unit of the kneading area of the terminal OH group capping agent
and the full-flight unit on a downstream side. The adhesion of a
carbonized material was also seen in the boundary between the back
flight unit of the addition and kneading area of the catalyst
deactivator and the full-flight unit on a downstream side. Further,
the maximum number of foreign substances contained in the aromatic
polycarbonate as a final product was 100 or more during
operation.
EXAMPLE 6
[0281] 2,2-bis(4-hydroxyphenyl)propane and diphenyl carbonate were
charged into a dissolution tank equipped with a stirrer in a molar
ratio of 1:1.02 and dissolved after the inside of the tank was
substituted by nitrogen.
[0282] Thereafter, the mixed solution was supplied continuously to
a vertical agitation tank equipped with a fractionating column and
maintained at an inner temperature of 220.degree. C. and an inner
pressure of 1.333.times.10.sup.4 Pa (100 mmHg), a disodium salt of
bisphenol A and tetramethyl ammonium hydroxide were added
continuously in amounts of 5.times.10.sup.-7 equivalent and
1.times.10.sup.-4 equivalent based on 1 mol of
2,2-bis(4-hydroxyphenyl)propane, respectively, and a reaction was
carried out by removing the formed phenol from the fractionating
column. The obtained reaction product (1) was discharged
continuously using a gear pump.
[0283] The reaction product (1) was then supplied continuously to a
vertical agitation tank equipped with a fractionating column
maintained at an inner temperature of 250.degree. C. and an inner
pressure of 1.333.times.10.sup.3 Pa (10 mmHg). A reaction was
carried out by removing the formed phenol from the fractionating
column. The obtained reaction product (2) was discharged
continuously using a gear pump.
[0284] The reaction product (2) was then supplied continuously to a
horizontal reactor maintained at an inner temperature of
270.degree. C. and an inner pressure of 1.333.times.10.sup.2 Pa (1
mmHg). A polycarbonate having a viscosity average molecular weight
of 15,300 was obtained continuously by further carrying out
polymerization while the formed phenol was removed from the system.
This polycarbonate contained 170 ppm of phenol and 250 ppm of
diphenyl carbonate.
[0285] This polycarbonate was then supplied continuously in a
molten state to an intermeshing twin screw extruder comprising 4
modules each of which has a solution adding and kneading area and a
vent area. A tetrabutyl phosphonium salt of dodecylbenzenesulfonic
acid was added to and kneaded into the polycarbonate continuously
as a 0.02 wt% aqueous solution in an amount of 2 equivalent based
on 1 equivalent of a disodium salt of bisphenol A (2 mols based on
1 equivalent of a disodium salt of bisphenol A) used as a
polymerization catalyst in the solution adding and kneading area of
the first module at a pressure of 1.5 MPa, water was removed from
the vent of the first module maintained at a pressure of
2.0.times.10.sup.3 Pa (15 mmHg) to deactivate the polymerization
catalyst, and part of volatile components contained in the polymer
was removed. Thereafter, water was added continuously to the
solution adding and kneading areas of the second to fourth modules
in an amount of 1 wt% based on 100 parts by weight of the
polycarbonate per unit module at a pressure of 1.5 MPa and kneaded
in the four modules for a total time of 20 seconds. Volatile
components contained in the polycarbonate were removed by reducing
the pressure of the vent area right after each of the solution
adding and kneading areas to 2.0.times.10.sup.3 Pa (15 mmHg), and
the obtained polycarbonate was extruded from a dice and then
pelletized by a pelletizer to obtain a polycarbonate as a final
product.
[0286] The measurement results of the amounts of the residual
phenol and diphenyl carbonate contained in the obtained
polycarbonate and the viscosity average molecular weight and color
b value of the polycarbonate are shown in Table 1.
EXAMPLES 7 to 16
[0287] Polycarbonates were obtained in the same manner as in
Example 6 except that the kneading pressure was changed in Examples
7 and 8, the kneading time was changed in Examples 9 and 10, the
amount of water was changed in Examples 11 and 12, the resin
temperature was changed in Examples 13 and 14, and the vent
pressure was changed in Examples 15 and 16 as shown in Table 1. The
measurement results of the amounts of the residual phenol and
diphenyl carbonate contained in the obtained polycarbonate and the
viscosity average molecular weight and color b value of the
polycarbonate are shown in Table 1.
1 TABLE 1 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 amount of catalyst
disodium salt of bisphenol A 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 (Note 1) (equivalent) tetramethyl
ammonium hydroxide 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1 .times.
10.sup.-4 (equivalent) amount of catalyst tetrabutylphosphonium
salt of 2 2 2 2 2 2 deactivator (Note 2) dodecylbenzenesulfonic
acid (equivalent) operation conditions kneading pressure (MPa) 1.5
0.5 3 1.5 1.5 1.5 of twin screw kneading time (seconds) 20 20 20 10
30 20 extruder amount of water (wt %) (Note 3) 1 1 1 1 1 0.5 resin
temperature (.degree. C.) 290 290 290 290 290 290 vent pressure
(.times.1000 Pa) 2 2 2 2 2 2 experimental results viscosity average
molecular 15300 15300 15200 15300 15100 15300 weight color b value
0.4 0.4 0.5 0.3 0.6 0.3 amount of residual phenol (ppm) 18 25 15 19
12 20 amount of residual diphenyl 42 50 36 45 34 40 carbonate (ppm)
Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 amount of catalyst disodium salt
of bisphenol A 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 5 .times. 10.sup.-7 (Note 1)
(equivalent) tetramethyl ammonium hydroxide 1 .times. 10.sup.-4 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1 .times.
10.sup.-4 (equivalent) amount of catalyst tetrabutylphosphonium
salt of 2 2 2 2 2 deactivator (Note 2) dodecylbenzenesulfonic acid
(equivalent) operation conditions kneading pressure (MPa) 1.5 1.5
1.5 1.5 1.5 of twin screw kneading time (seconds) 20 20 20 20 20
extruder amount of water (wt %) (Note 3) 2 1 1 1 1 resin
temperature (.degree. C.) 290 270 320 290 290 vent pressure
(.times.1000 Pa) 2 2 2 0.667 4 experimental results viscosity
average molecular 15200 15300 15100 15300 15300 weight color b
value 0.4 0.2 0.5 0.4 0.4 amount of residual phenol (ppm) 17 23 13
10 25 amount of residual diphenyl 41 44 34 30 55 carbonate (ppm)
Note 1) amount of catalyst based on 1 mol of
2,2-bis(4-hydroxyphenyl)prop- ane Note 2) amount of catalyst
deactivator based on 1 equivalent of disodium salt of bisphenol A
Note 3) amount of water based on throughput of polycarbonate per
unit module
EXAMPLE 17
[0288] A polycarbonate was produced in the same manner as in
Example 6 except that a tetrabutyl ammonium salt of
paratoluenesulfonic acid was used as a catalyst deactivator in an
amount shown in Table 2. The measurement results of the amounts of
the residual phenol and diphenyl carbonate contained in the
obtained polycarbonate and the viscosity average molecular weight
and color b value of the polycarbonate are shown in Table 2.
EXAMPLE 18
[0289] A polycarbonate was produced in the same manner as in
Example 6 except that butyl paratoluenesulfonate was used as a
catalyst deactivator in an amount shown in Table 2. The measurement
results of the amounts of the residual phenol and diphenyl
carbonate contained in the obtained polycarbonate and the viscosity
average molecular weight and color b value of the polycarbonate are
shown in Table 2.
2 TABLE 2 Ex. 17 Ex. 18 amount of catalyst disodium salt of
bisphenol A (equivalent) 5 .times. 10.sup.-7 5 .times. 10.sup.-7
(Note 1) tetramethyl ammonium hydroxide 1 .times. 10.sup.-4 1
.times. 10.sup.-4 (equivalent) amount of catalyst tetrabutyl
ammonium salt of 2 deactivator (Note 2) paratoluenesulfonic acid
(equivalent) butyl paratoluenesulfonate (equivalent) 2 operation
conditions kneading pressure (MPa) 1.5 1.5 of twin screw kneading
time (seconds) 20 20 extruder amount of water (wt %) (Note 3) 1 1
resin temperature (.degree. C.) 290 290 vent pressure (.times.1000
Pa) 2 2 experimental results viscosity average molecular weight
15300 15300 color b value 0.3 0.6 amount of residual phenol (ppm)
19 23 amount of residual diphenyl carbonate 41 40 (ppm) Note 1)
amount of catalyst based on 1 equivalent of
2,2-bis(4-hydroxyphenyl)propane Note 2) amount of catalyst
deactivator based on 1 equivalent of disodium salt of bisphenol A
Note 3) amount of water based on throughput of polycarbonate per
unit module
EXAMPLES 19 and 20
[0290] Polycarbonates were produced in the same manner as in
Example 6 except that the amount of the catalyst and the amount of
the catalyst deactivator were changed as shown in Table 3. The
measurement results of the amounts of the residual phenol and
diphenyl carbonate contained in each of the obtained polycarbonates
and the viscosity average molecular weight and color b value of
each of the polycarbonates are shown in Table 3.
Referential Example
[0291] A polycarbonate was produced in the same manner as in
Example 6 except that the kneading pressure out of the operation
conditions of the twin screw extruder was changed as shown in Table
3. The measurement results of the amounts of the residual phenol
and diphenyl carbonate contained in the obtained polycarbonate and
the viscosity average molecular weight and color b value of the
polycarbonate are shown in Table 3.
3 TABLE 3 Ex. 19 Ex. 20 R. Ex. amount of catalyst disodium salt of
bisphenol A 1 .times. 10.sup.-6 2 .times. 10.sup.-6 5 .times.
10.sup.-7 (Note 1) (equivalent) tetramethyl ammonium hydroxide 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4
(equivalent) amount of catalyst tetrabutylphosphonium salt of 2 2 2
deactivator (Note 2) dodecylbenzenesulfonic acid (equivalent)
operation conditions kneading pressure (MPa) 1.5 1.5 0.1 of twin
screw kneading time (seconds) 20 20 20 extruder amount of water (wt
%) (Note 3) 1 1 1 resin temperature (.degree. C.) 290 290 290 vent
pressure (.times.1000 Pa) 2 2 2 experimental results viscosity
average molecular 15300 15300 15300 weight color b value 0.5 0.7
0.4 amount of residual phenol (ppm) 20 19 50 amount of residual
diphenyl 39 40 150 carbonate (ppm) Note 1) amount of catalyst based
on 1 equivalent of 2,2-bis(4-hydroxyphenyl)propane Note 2) amount
of catalyst deactivator based on 1 equivalent of disodium salt of
bisphenol A Note 3) amount of water based on throughput of
polycarbonate per unit module R. Ex.: Referential Example
EXAMPLE 21
[0292] 2,2-bis(4-hydroxyphenyl)propane and diphenyl carbonate were
charged into a dissolution tank equipped with a stirrer in a molar
ratio of 1:1.02 and dissolved after the inside of the tank was
substituted by nitrogen.
[0293] Thereafter, the mixed solution was supplied continuously to
a vertical agitation tank equipped with a fractionating column and
maintained at an inner temperature of 220.degree. C. and an inner
pressure of 1.333.times.10.sup.4 Pa (100 mmHg), a disodium salt of
bisphenol A and tetramethyl ammonium hydroxide were added
continuously in amounts of 5.times.10 .sup.-7 equivalent and
1.times.10.sup.-4 equivalent based on 1 mol of
2,2-bis(4-hydroxyphenyl)propane, respectively, and a reaction was
carried out by removing the formed phenol from the fractionating
column. The obtained reaction product (1) was discharged
continuously using a gear pump.
[0294] The reaction product (1) was then supplied continuously to a
vertical agitation tank equipped with a fractionating column
maintained at an inner temperature of 250.degree. C. and an inner
pressure of 1.333.times.10.sup.3 Pa (10 mmHg). A reaction was
carried out by removing the formed phenol from the fractionating
column. The obtained reaction (2) product was discharged
continuously using a gear pump.
[0295] The reaction product (2) was then supplied continuously to a
horizontal reactor maintained at an inner temperature of
270.degree. C. and an inner pressure of 1.333.times.10.sup.2 Pa (1
mmHg). A polycarbonate having a viscosity average molecular weight
of 15,200 was obtained continuously by further carrying out
polymerization while the formed phenol was removed from the system.
This polycarbonate contained 180 ppm of phenol and 240 ppm of
diphenyl carbonate.
[0296] This polycarbonate was supplied continuously in a molten
state to an intermeshing twin screw extruder comprising 4 modules
having a solution adding and kneading area and a vent area. A
tetrabutyl phosphonium salt of dodecylbenzenesulfonic acid was
added to and kneaded into the polycarbonate continuously as a 0.02
wt% aqueous solution in an amount of 2 equivalents based on 1
equivalent of a disodium salt of bisphenol A used as a
polymerization catalyst in the solution adding and kneading area of
the first module, then water was removed from the vent of the first
module maintained at a pressure of 2.0.times.10.sup.3 Pa (15 mmHg)
to deactivate the polymerization catalyst, and part of volatile
components contained in the polymer was removed. Thereafter, water
was added to and kneaded into the polycarbonate continuously in the
solution adding and kneading areas of the second to fourth modules
in an amount of 1 wt% based on the polycarbonate, volatile
components contained in the polycarbonate were removed by reducing
the pressure of the vent area right after each of the solution
adding and kneading areas to 2.0.times.10.sup.3 Pa (15 mmHg), and
the polycarbonate was extruded from a dice and then pelletized by a
pelletizer to obtain a polycarbonate as a final product.
[0297] The measurement results of the amounts of the residual
phenol and diphenyl carbonate contained in the obtained
polycarbonate and the viscosity average molecular weight and color
b value of the polycarbonate are shown in Table 4.
EXAMPLES 22 to 32
[0298] Polycarbonates were produced in the same manner as in
Example 21 except that the amount of the mixed solution and the
amount of water were changed in Examples 22 and 23, the kneading
time was changed in Examples 24 and 25, the amount of the catalyst
deactivator was changed in Examples 26 and 27, the resin
temperature was changed in Examples 28, 29 and 30, and the vent
pressure was changed in Examples 31 and 32 as shown in Table 4. The
measurement results of the amounts of the residual phenol and
diphenyl carbonate contained in each of the obtained polycarbonates
and the viscosity average molecular weight and color b value of
each of the polycarbonates are shown in Table 4.
4 TABLE 4 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 amount of
catalyst disodium salt of bisphenol A 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 (Note 1) (equivalent) tetramethyl
ammonium hydroxide 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1 .times.
10.sup.-4 (equivalent) amount of catalyst tetrabutylphosphonium
salt of 2 2 2 2 2 1 deactivator (Note 2) dodecylbenzenesulfonic
acid (equivalent) operation amount of mixed solution (wt %) 1 0.3 3
1 1 1 conditions of twin (Note 3) screw extruder amount of water
(wt %) (Note 4) 1 0.3 3 1 1 1 kneading time of unit module
(seconds) 4.5 4.5 4.5 1.5 18 4.5 kneading time of total module
(seconds) 18 18 18 6 72 18 resin temperature (.degree. C.) 290 290
290 290 290 290 vent pressure (.times.1000 Pa) 2 2 2 2 2 2
experimental viscosity average molecular weight 15200 15200 15200
15200 15100 15200 results color b value 0.3 0.5 0.5 0.4 0.5 0.3
amount of residual phenol (ppm) 15 20 18 22 14 15 amount of
residual diphenyl 50 52 51 53 49 50 carbonate (ppm) Ex. 27 Ex. 28
Ex. 29 Ex. 30 Ex. 31 Ex. 32 amount of catalyst disodium salt of
bisphenol A 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 (Note 1) (equivalent) tetramethyl ammonium hydroxide 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1 .times.
10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 (equivalent)
amount of catalyst tetrabutylphosphonium salt of 10 2 2 2 2 2
deactivator (Note 2) dodecylbenzenesulfonic acid (equivalent)
operation amount of mixed solution (wt %) 1 1 1 1 1 1 conditions of
twin (Note 3) screw extruder amount of water (wt %) (Note 4) 1 1 1
1 1 1 kneading time of unit module (seconds) 4.5 4.5 4.5 4.5 4.5
4.5 kneading time of total module (seconds) 18 18 18 18 18 18 resin
temperature (.degree. C.) 290 220 340 380 290 290 vent pressure
(.times.1000 Pa) 2 2 2 2 0.667 4 experimental viscosity average
molecular weight 15200 15300 15100 14900 15200 15200 results color
b value 0.6 0.2 0.6 2.0 0.4 0.5 amount of residual phenol (ppm) 17
20 21 80 10 25 amount of residual diphenyl 53 55 45 43 25 56
carbonate (ppm) Note 1) amount of catalyst based on 1 equivalent of
2,2-bis(4-hydroxyphenyl)propa- ne Note 2) amount of catalyst
deactivator based on 1 equivalent of disodium salt of bisphenol A
Note 3) amount of mixed solution based on throughput of
polycarbonate in the first module Note 4) amount of water based on
throughput of polycarbonate in the second to fourth modules
EXAMPLE 33
[0299] A polycarbonate was produced in the same manner as in
Example 21 except that a tetrabutyl ammonium salt of
paratoluenesulfonic acid was used as a catalyst deactivator in an
amount shown in Table 5. The measurement results of the amounts of
the residual phenol and diphenyl carbonate contained in the
obtained polycarbonate and the viscosity average molecular weight
and color b value of the polycarbonate are shown in Table 5.
EXAMPLE 33
[0300] A polycarbonate was produced in the same manner as in
Example 21 except that butyl paratoluenesulfonate was used as a
catalyst deactivator in an amount shown in Table 5. The measurement
results of the amounts of the residual phenol and diphenyl
carbonate contained in the obtained polycarbonate and the viscosity
average molecular weight and color b value of the polycarbonate are
shown in Table 5.
5 TABLE 5 Ex. 33 Ex. 34 amount of catalyst disodium salt of
bisphenol A 5 .times. 10.sup.-7 5 .times. 10.sup.-7 (Note 1)
(equivalent) tetramethyl ammonium hydroxide 1 .times. 10.sup.-4 1
.times. 10.sup.-4 (equivalent) amount of catalyst tetrabutyl
ammonium salt of 2 deactivator paratoluenesulfonic acid
(equivalent) (Note 2) butyl paratoluenesulfonate 2 (equivalent)
operation amount of mixed solution (wt %) 1 1 conditions of twin
(Note 3) screw extruder amount of water (wt %) (Note 4) 1 1
kneading time of unit module (seconds) 4.5 4.5 kneading time of
total module (seconds) 18 18 resin temperature (.degree. C.) 290
290 vent pressure (.times.1000 Pa) 2 2 experimental viscosity
average molecular weight 15200 15100 results color b value 0.4 0.7
amount of residual phenol (ppm) 18 25 amount of residual diphenyl
carbonate 49 55 (ppm) Note 1) amount of catalyst based on 1
equivalent of 2,2-bis(4-hydroxyphenyl)propane Note 2) amount of
catalyst deactivator based on 1 equivalent of disodium salt of
bisphenol A
EXAMPLES 35 and 36
[0301] Polycarbonates were produced in the same manner as in
Example 21 except that the amount of the catalyst and the amount of
the catalyst deactivator were changed as shown in Table 6. The
measurement results of the amounts of the residual phenol and
diphenyl carbonate contained in each of the obtained polycarbonates
and the viscosity average molecular weight and color b value of
each of the polycarbonates are shown in Table 6.
EXAMPLES 37 to 39
[0302] Polycarbonates were produced in the same manner as in
Example 21 except that the amount of the mixed solution and the
amount of water were changed in Examples 37 and 38 and the kneading
time was changed in Example 39 as shown in Table 6. The measurement
results of the amounts of the residual phenol and diphenyl
carbonate contained in each of the obtained polycarbonates and the
viscosity average molecular weight and color b value of each of the
polycarbonates are shown in Table 6.
6 TABLE 6 Ex. 35 Ex. 36 Ex. 37 Ex. 38 Ex. 39 amount of catalyst
disodium salt of bisphenol A 1 .times. 10.sup.-6 2 .times.
10.sup.-6 5 .times. 10.sup.-7 5 .times. 10.sup.-7 5 .times.
10.sup.-7 (Note 1) (equivalent) tetramethyl ammonium hydroxide 1
.times. 10.sup.-4 1 .times. 10.sup.-4 1 .times. 10.sup.-4 1 .times.
10.sup.-4 1 .times. 10.sup.-4 (equivalent) amount of catalyst
tetrabutylphosphonium salt of 2 2 2 2 2 deactivator (Note 2)
dodecylbenzenesulfonic acid (equivalent) operation amount of mixed
solution (wt %) 1 1 0.03 30 1 conditions of twin (Note 3) screw
extruder amount of water (wt %) (Note 4) 1 1 0.03 30 1 kneading
time of unit module (seconds) 4.5 4.5 4.5 4.5 30 kneading time of
total module (seconds) 18 18 18 18 120 resin temperature (.degree.
C.) 290 290 290 290 290 vent pressure (.times.1000 Pa) 2 2 2 2 2
experimental viscosity average molecular weight 15200 15200 15200
15000 14900 results color b value 0.6 0.7 0.4 0.9 1.5 amount of
residual phenol (ppm) 20 19 20 20 102 amount of residual diphenyl
45 40 100 54 52 carbonate (ppm) Note 1) amount of catalyst based on
1 equivalent of 2,2-bis(4-hydroxyphenyl)propane Note 2) amount of
catalyst deactivator based on 1 equivalent of disodium salt of
bisphenol A Note 3) amount of mixed solution based on throughput of
polycarbonate in the first module Note 4) amount of water based on
throughput of polycarbonate in the second to fourth modules
EXAMPLE 40
[0303] A polycarbonate having a viscosity average molecular weight
of 15,200 was obtained by adding a disodium salt of bisphenol A and
tetramethyl ammonium hydroxide continuously to a mixed solution of
2,2-bis(4-hydroxyphenyl)propane and diphenyl carbonate in a molar
ratio of 1:1.02 in amounts of 5.times.10.sup.-7 equivalent and
1.times.10.sup.-4 equivalent based on 1 mol of
2,2-bis(4-hydroxyphenyl)pr- opane, respectively, and by carrying
out a reaction by removing the formed phenol and subjected to a
post-treatment using equipment shown in FIG. 3.
[0304] The obtained polycarbonate was supplied continuously to a
intermeshing twin screw extruder (reference numeral 21 in FIG. 3)
comprising 4 modules, each consisting of a kneading unit, a seal
ring unit, a back kneading unit and a full-flight unit.
[0305] In the intermeshing twin screw extruder (21 in FIG. 3), a
0.02 wt% aqueous solution of a catalyst deactivator (tetrabutyl
phosphonium salt of dodecylbenzenesulfonic acid) was added to and
kneaded into the polycarbonate in the adding and kneading area of
the first module in an amount of 1 wt% based on the polycarbonate
from a liquid injection nozzle (22 in FIG. 3) and the extruder was
evacuated at a vent pressure of 2.0.times.10.sup.3 Pa in the vent
of the first module. Thereafter, pure water was added to and
kneaded into the polycarbonate in an amount of 1 wt% based on the
polycarbonate from liquid injection nozzles (23, 24 and 25 in FIG.
3) in each module and the extruder was evacuated at a vent pressure
of 2.0.times.10.sup.3 Pa.
[0306] A water scrubber condenser was connected to the vent of the
twin screw extruder and a vacuum pump (1 in FIG. 3) and pure water
having a temperature of 10.degree. C. was supplied from two sprays
at a flow rate 200 times the total amount of water used as a
devolatilizing agent per a spray. A solid cone spray nozzle shown
in FIG. 5 was used in the scrubber.
[0307] The scrubbing solution discharged from the scrubber was
supplied to a scrubbing solution storage tank (7 in FIG. 3)
connected by a scrubbing solution line (11 in FIG. 3), mixed
thoroughly by a stirrer and discharged continuously from a
scrubbing solution line (12 in FIG. 3) provided at the bottom of
the scrubbing solution storage tank by a scrubbing solution pump
(13 in FIG. 3).
[0308] The scrubbing solution discharged by the pump was further
supplied and filtered by a 1 .mu.m-mesh cartridge filter (14 in
FIG. 3) connected by a scrubbing solution line (15 in FIG. 3),
supplied to a plate heat exchanger (18 in FIG. 3) to be re-cooled
at 10.degree. C. and recycled to the scrubber condenser.
[0309] A vapor line (9 in FIG. 3) for connecting the intermeshing
twin screw extruder (21 in FIG. 3) and the scrubber and a vacuum
line for connecting the scrubber and the vacuum pump (1 in FIG. 3)
were kept warm with steam. The vapor inlet portion of the scrubber
(5 in FIG. 3) was covered with a steam jacket to prevent the
deposition of a low-boiling product by local cooling.
[0310] In this example, 30 days of continuous operation is possible
without a problem and volatile components removed during this were
collected by the cartridge filter.
[0311] When the vacuum collection system was disassembled and
inspected after 30 days of continuous operation, the adhesion of
foreign substances to the inside of the equipment was not seen and
it was confirmed that smooth continuous operation was possible.
* * * * *