U.S. patent application number 15/766208 was filed with the patent office on 2018-10-11 for diaryl carbonate and method for producing the same, and method for producing an aromatic polycarbonate resin.
This patent application is currently assigned to MITSUBISHI GAS CHEMICAL COMPANY, INC.. The applicant listed for this patent is MITSUBISHI GAS CHEMICAL COMPANY, INC.. Invention is credited to Hidefumi HARADA, Yoshinori ISAHAYA, Jungo TAGUCHI.
Application Number | 20180290989 15/766208 |
Document ID | / |
Family ID | 58517174 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180290989 |
Kind Code |
A1 |
HARADA; Hidefumi ; et
al. |
October 11, 2018 |
DIARYL CARBONATE AND METHOD FOR PRODUCING THE SAME, AND METHOD FOR
PRODUCING AN AROMATIC POLYCARBONATE RESIN
Abstract
A diaryl carbonate containing a compound of the following
formula (I) in an amount of less than 1,000 ppm by mass, and a
method for producing the same: ##STR00001## wherein R.sup.1
represents a hydrogen atom, a halogen atom, an alkyl group, an
alkoxy group, an aryl group, or an aryloxy group.
Inventors: |
HARADA; Hidefumi; (Hyogo,
JP) ; TAGUCHI; Jungo; (Saitama, JP) ; ISAHAYA;
Yoshinori; (Ibaraki, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI GAS CHEMICAL COMPANY, INC. |
Tokyo |
|
JP |
|
|
Assignee: |
MITSUBISHI GAS CHEMICAL COMPANY,
INC.
Tokyo
JP
|
Family ID: |
58517174 |
Appl. No.: |
15/766208 |
Filed: |
October 12, 2016 |
PCT Filed: |
October 12, 2016 |
PCT NO: |
PCT/JP2016/080174 |
371 Date: |
April 5, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 3/4211 20130101;
C07D 265/26 20130101; C07C 68/08 20130101; C08G 64/04 20130101;
C07C 69/96 20130101; C07C 68/00 20130101; C07B 61/00 20130101; B01D
9/0031 20130101; C07C 68/06 20130101; C08G 64/30 20130101; C07C
68/00 20130101; C07C 69/96 20130101; C07C 68/06 20130101; C07C
69/96 20130101; C07C 68/08 20130101; C07C 69/96 20130101 |
International
Class: |
C07D 265/26 20060101
C07D265/26; B01D 3/42 20060101 B01D003/42; B01D 9/00 20060101
B01D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 2015 |
JP |
2015-202941 |
Claims
1. A diaryl carbonate containing a compound of the following
formula (I) in an amount of less than 1,000 ppm by mass:
##STR00008## wherein R.sup.1 represents a hydrogen atom, a halogen
atom, an alkyl group, an alkoxy group, an aryl group, or an aryloxy
group.
2. A method for producing the diaryl carbonate according to claim
1, the method comprising: a first step of reacting urea with an
alkyl alcohol to yield a first reaction mixture containing a
dialkyl carbonate; a second step of reacting the dialkyl carbonate
in the first reaction mixture with an aryl alcohol to yield a
second reaction mixture containing an alkylaryl carbonate; a third
step of subjecting the alkylaryl carbonate in the second reaction
mixture to disproportionation to yield a third reaction mixture
containing a diaryl carbonate; and a fourth step of purifying the
third reaction mixture, wherein the third reaction mixture further
contains the compound of the formula (I) in an amount of 1,000 ppm
by mass or more.
3. The method according to claim 2, wherein the fourth step
comprises a distillation step of, using a distillation column,
obtaining the diaryl carbonate containing the compound of the
formula (I) in an amount of less than 1,000 ppm by mass from the
top of the column and obtaining a mixture having concentrated the
compound of the formula (I) from the bottom of the column, wherein
the distillation step is conducted under the following conditions
(a) and (b): (a) that the pressure at the top of the distillation
column is 0.01 to 10 kPa, and (b) that the reflux ratio is 2 to
20.
4. The method according to claim 3, which further comprises a fifth
step of filtering off the compound of the formula (I) which is
precipitated from the concentrated mixture at a temperature in the
range of from 80 to 230.degree. C.
5. The method according to claim 4, which further comprises a
recycling step (sixth step) of recovering the compound of the
chemical formula (I) filtered off in the fifth step and bringing
the filtrate back to the fourth step.
6. The method according to claim 2, wherein the alkyl alcohol used
in the first step is an alkyl alcohol having 3 to 6 carbon
atoms.
7. A method for producing an aromatic polycarbonate resin, the
method comprising performing melt polycondensation in the presence
of a transesterification catalyst using the diaryl carbonate
according to claim 1 and an aromatic dihydroxy compound.
8. The method according to claim 3, wherein the alkyl alcohol used
in the first step is an alkyl alcohol having 3 to 6 carbon
atoms.
9. The method according to claim 4, wherein the alkyl alcohol used
in the first step is an alkyl alcohol having 3 to 6 carbon
atoms.
10. The method according to claim 5, wherein the alkyl alcohol used
in the first step is an alkyl alcohol having 3 to 6 carbon atoms.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a diaryl carbonate and a
method for producing the same. In addition, the present invention
relates to a method for producing an aromatic polycarbonate resin
by a melt transesterification method using the diaryl
carbonate.
BACKGROUND ART
[0002] A diaryl carbonate is a compound which is advantageously
used as a raw material for a polycarbonate produced by a melt
transesterification method, and has conventionally been produced by
a reaction of an aromatic hydroxy compound and phosgene. However,
the production of a diaryl carbonate using phosgene is
disadvantageous not only in that phosgene is highly toxic and
highly likely to cause the apparatuses used in the production to
suffer corrosion, but also in that a great amount of an alkali is
required for neutralizing hydrogen chloride by-produced during the
reaction. Therefore, a method for producing a diaryl carbonate
without using phosgene is desired, and some attempts to develop
such a method have been made.
[0003] Among the attempts, a method suitable for producing a diaryl
carbonate especially from an industrial point of view has been
proposed in which a dialkyl carbonate is obtained from urea and an
alkyl alcohol having 3 to 6 carbon atoms, and then the dialkyl
carbonate and an aromatic hydroxy compound are subjected to
transesterification to obtain an alkylaryl carbonate, and the
obtained alkylaryl carbonate is subjected to disproportionation,
producing a diaryl carbonate (see, for example, patent document 1).
By reusing the by-produced alkyl alcohol as a raw material for the
dialkyl carbonate in this method, the method can produce a diaryl
carbonate from inexpensive urea and aromatic hydroxy compound.
PRIOR ART REFERENCE
Patent Document
[0004] Patent document 1: Japanese Unexamined Patent Publication
No. Hei 10-152456
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0005] The diaryl carbonate produced by the above-mentioned method
has a problem in that the diaryl carbonate has mixed thereinto the
by-produced nitrogen-containing compound and, when such a diaryl
carbonate is used in the subsequent process for producing an
aromatic polycarbonate resin by a melt transesterification method,
the nitrogen-containing compound inhibits a polymerization reaction
between the diaryl carbonate and an aromatic dihydroxy compound. In
view of the above-mentioned problem, an object of the present
invention is to provide a diaryl carbonate containing a reduced
amount of the nitrogen-containing compound which inhibits a
polymerization reaction.
Means for Solving the Problems
[0006] The present inventors have conducted extensive and intensive
studies with a view toward solving the above-mentioned problems. As
a result, it has been found that, by using a diaryl carbonate
containing a nitrogen-containing compound in an amount of less than
a specific amount, the above-mentioned problems accompanying the
method for producing an aromatic polycarbonate resin by a melt
transesterification method can be solved, and the present invention
has been completed. In addition, the present inventors have found a
method for producing the above diaryl carbonate.
[0007] The present invention is as follows.
[0008] [1] A diaryl carbonate containing a compound of the
following formula (I) in an amount of less than 1,000 ppm by
mass:
##STR00002##
wherein R.sup.1 represents a hydrogen atom, a halogen atom, an
alkyl group, an alkoxy group, an aryl group, or an aryloxy
group.
[0009] [2] A method for producing the diaryl carbonate according to
item [1] above, wherein the method comprises:
[0010] a first step of reacting urea with an alkyl alcohol to yield
a first reaction mixture containing a dialkyl carbonate;
[0011] a second step of reacting the dialkyl carbonate in the first
reaction mixture with an aromatic hydroxy compound to yield a
second reaction mixture containing an alkylaryl carbonate;
[0012] a third step of subjecting the alkylaryl carbonate in the
second reaction mixture to disproportionation to yield a third
reaction mixture containing a diaryl carbonate; and
[0013] a fourth step of purifying the third reaction mixture,
[0014] wherein the third reaction mixture further contains the
compound of the formula (I) in an amount of 1,000 ppm by mass or
more.
[0015] [3] The method according to item [2] above, wherein the
fourth step comprises a distillation step of, using a distillation
column, obtaining the diaryl carbonate containing the compound of
the formula (I) in an amount of less than 1,000 ppm by mass from
the top of the column and obtaining a mixture having concentrated
the compound of the formula (I) from the bottom of the column,
wherein the distillation step is conducted under the following
conditions (a) and (b):
[0016] (a) that the pressure at the top of the distillation column
is 0.01 to 10 kPa, and
[0017] (b) that the reflux ratio is 2 to 20.
[0018] [4] The method according to item [3] above, which further
comprises a fifth step of filtering off the compound of the formula
(I) which is precipitated from the concentrated mixture at a
temperature in the range of from 80 to 230.degree. C.
[0019] [5] The method according to item [4] above, which further
comprises a recycling step (sixth step) of recovering the compound
of the formula (I) filtered off in the fifth step and bringing the
filtrate back to the fourth step.
[0020] [6] The method according to any one of items [2] to [5]
above, wherein the alkyl alcohol used in the first step is an alkyl
alcohol having 3 to 6 carbon atoms.
[0021] [7] A method for producing an aromatic polycarbonate resin,
wherein the method comprises performing melt polycondensation in
the presence of a transesterification catalyst using the diaryl
carbonate according to item [1] above and an aromatic dihydroxy
compound.
Effects of the Invention
[0022] In the production of an aromatic polycarbonate by a melt
transesterification method, by using a diaryl carbonate containing
the compound of the formula (I) in an amount of less than 1,000 ppm
by mass, the polymerization time can be reduced, as compared to
that in the production of an aromatic polycarbonate using a diaryl
carbonate produced by a conventional method. Therefore, the present
invention has a remarkable effect from an industrial viewpoint.
BRIEF DESCRIPTION OF THE DRAWING
[0023] FIG. 1 A graph showing a change with the temperature of the
solubility of 2H-1,3-benzoxazine-2,4(3H)-dione (BOD) in diphenyl
carbonate (DPC).
MODE FOR CARRYING OUT THE INVENTION
[0024] The terms used in the present invention are defined as
described below unless otherwise specified.
[0025] In the present specification, the term "step" means not only
an independent step but also a combination of steps which cannot be
clearly distinguished from one another as long as a desired purpose
of the steps is achieved. Further, the range of values indicated
using the preposition "to" means a range of values including the
respective values shown before and after the preposition "to" as
the minimum value and the maximum value. Furthermore, with respect
to the amount of the component of a mixture, when a plurality of
materials corresponding to the components are present in the
mixture, the amount of the components in the mixture means the
total amount of the materials present in the mixture unless
otherwise specified.
[0026] In the present invention, the term "halogen atom" means a
fluorine atom, a chlorine atom, a bromine atom, or an iodine
atom.
[0027] In the present invention, the term "alkyl group" means a
monovalent group of linear, branched, or cyclic saturated aliphatic
hydrocarbon unless otherwise specified. Examples of "alkyl groups
having 1 to 10 carbon atoms" include a methyl group, an ethyl
group, a n-propyl group, an isopropyl group, a cyclopropyl group, a
n-butyl group, an isobutyl group, a s-butyl group, a t-butyl group,
a cyclobutyl group, a pentyl group, a cyclopentyl group, a hexyl
group, a cyclohexyl group, a heptyl group, a cycloheptyl group, an
octyl group, a cyclooctyl group, a nonyl group, a cyclononyl group,
a decyl group, and a cyclodecyl group (including their isomers).
These include examples of "alkyl groups having 1 to 6 carbon atoms"
and examples of "alkyl groups having 3 to 6 carbon atoms".
[0028] In the present invention, the term "alkoxy group" means a
--O-alkyl group (wherein the alkyl is as defined above) unless
otherwise specified. In the present invention, preferred examples
of alkoxy groups include "alkoxy groups having 1 to 6 carbon
atoms", such as a methoxy group, an ethoxy group, a n-propyloxy
group, an isopropyloxy group, a cyclopropyloxy group, a n-butyloxy
group, an isobutyloxy group, a s-butyloxy group, a t-butyloxy
group, a cyclobutyloxy group, a pentyloxy group, a cyclopentyloxy
group, a hexyloxy group, and a cyclohexyloxy group (including their
isomers).
[0029] In the present invention, the term "aryl group" means a
monovalent group of monocyclic or polycyclic aromatic hydrocarbon
unless otherwise specified. In the present invention, preferred
examples of aryl groups include "aryl groups having 6 to 10 carbon
atoms", such as a phenyl group, a naphthyl group, and an anthryl
group. An especially preferred example of aryl group is a phenyl
group. The "aryl group" may be substituted with an alkyl group
having 1 to 6 carbon atoms.
[0030] In the present invention, the term "aryloxy group" means a
--O-aryl group (wherein the aryl is as defined above). In the
present invention, preferred examples of aryloxy groups include
"aryloxy groups having 6 to 10 carbon atoms", such as a phenoxy
group, a naphthyloxy group, and an anthryloxy group. An especially
preferred example of aryloxy group is a phenoxy group.
[0031] <Diaryl Carbonate>
[0032] The present invention is directed to a diaryl carbonate
containing a compound of the following formula (I):
##STR00003##
wherein R.sup.1 represents a hydrogen atom, a halogen atom, an
alkyl group, an alkoxy group, an aryl group, or an aryloxy group in
an amount of less than 1,000 ppm by mass.
[0033] The diaryl carbonate of the present invention is
specifically a diaryl carbonate which is represented by the
following formula (6):
ArO--CO--OAr (6)
wherein Ar represents a phenyl group, or a phenyl group substituted
with a halogen atom, an alkyl group, an alkoxy group, an aryl
group, or an aryloxy group, and which contains the compound of the
formula (I) in an amount of less than 1,000 ppm by mass.
[0034] When Ar is a phenyl group, the diaryl carbonate of the
present invention is diphenyl carbonate (which is frequently
referred to as "DPC" in the present specification) containing the
compound of the formula (I) wherein R.sup.1 is a hydrogen atom
(2H-1,3-benzoxazine-2,4(3H)-dione (which is frequently referred to
as "BOD" in the present specification)), in an amount of less than
1,000 ppm by mass.
[0035] When Ar is a phenyl group substituted with a halogen atom,
an alkyl group, an alkoxy group, an aryl group, or an aryloxy
group, the diaryl carbonate of the present invention is that
containing the compound of the formula (I) wherein R.sup.1 is the
same as the substituent for Ar, in an amount of less than 1,000 ppm
by mass.
[0036] A specific embodiment of the present invention is DPC
containing BOD in an amount of less than 1,000 ppm by mass.
[0037] The amount of the compound of the formula (I) contained in
the diaryl carbonate of the present invention is 0.1 to less than
1,000 ppm by mass, preferably 900 ppm by mass or less, more
preferably 800 ppm by mass or less, especially preferably 700 ppm
by mass or less.
[0038] The diaryl carbonate of the present invention is produced by
a method using urea, an alkyl alcohol, and an aromatic hydroxy
compound, typically by the below-described <Method for producing
a diaryl carbonate> of the present invention.
[0039] <Method for Producing a Diaryl Carbonate>
[0040] The present invention is also directed to a method for
producing a diaryl carbonate which contains a compound of the
following formula (I):
##STR00004##
wherein R.sup.1 represents a hydrogen atom, a halogen atom, an
alkyl group, an alkoxy group, an aryl group, or an aryloxy group in
an amount of less than 1,000 ppm by mass. The method comprises:
[0041] a first step of reacting urea with an alkyl alcohol to yield
a first reaction mixture containing a dialkyl carbonate;
[0042] a second step of reacting the dialkyl carbonate with an
aromatic hydroxy compound to yield a second reaction mixture
containing an alkylaryl carbonate;
[0043] a third step of subjecting the alkylaryl carbonate to
disproportionation to yield a third reaction mixture containing a
diaryl carbonate; and
[0044] a fourth step of purifying the reaction mixture,
[0045] wherein the third reaction mixture further contains the
compound of the formula (I) in an amount of 1,000 ppm by mass or
more.
[0046] (First Step)
[0047] In the first step, a reaction of urea with an alkyl alcohol
is performed to yield a first reaction mixture containing a dialkyl
carbonate. The alkyl alcohol used in the first step is represented
by the following formula (1):
R--OH (1)
wherein R represents an alkyl group, preferably an alkyl group
having 3 to 6 carbon atoms. Examples of the alkyl alcohols include
n-propanol, isopropanol, n-butanol, isobutanol, s-butanol,
t-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol,
2-methyl-2-butanol, 3-methyl-1-butanol, 3-methyl-2-butanol,
2,2-dimethyl-1-propanol, cyclopentanol, 1-hexanol, 2-hexanol,
3-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol,
4-methyl-1-pentanol, 2,2-dimethyl-1-butanol,
2,3-dimethyl-1-butanol, 3,3-dimethyl-1-butanol, 2-ethyl-1-butanol,
and 3-ethyl-1-butanol.
[0048] In the reaction of urea with an alkyl alcohol, an alkyl
carbamate of the following formula (2):
RO--CO--NH.sub.2 (2)
wherein R is as defined above is first yielded, and then further
reacted with the alkyl alcohol to yield a dialkyl carbonate of the
following formula (3):
RO--CO--OR (3)
wherein R is as defined above. Generally, a reaction in which urea
is transformed to an alkyl carbamate is fast, and a reaction in
which the alkyl carbamate is transformed to a dialkyl carbonate is
slow. Preferred reaction conditions for the respective stages of
reactions are different from each other. Therefore, when the
reactions are conducted in a continuous manner, it is necessary to
perform the reactions in two separate stages, but, when the
reactions are conducted in a batch-wise manner, the reactions can
be successively performed in the same reactor.
[0049] With respect to the stage in which an alkyl carbamate is
produced from urea, the reaction is fast and therefore can be
conducted at a relatively low temperature. A preferred reaction
temperature is 100 to 200.degree. C. When the reaction in this
stage is performed at too high a temperature, a side reaction
disadvantageously occurs. The reaction pressure is preferably
atmospheric pressure to about 2 MPa. In this reaction, ammonia is
formed and therefore, by providing the system with, for example, a
pressure control valve, the reaction may be conducted while
appropriately removing ammonia from the system so as to maintain
the inside of the system at a predetermined pressure. For
selectively removing only ammonia from the system, it is preferred
that the reactor is provided with a distillation column at the
upper portion thereof. The reaction time is about 1 to 4 hours. The
reaction can be performed while allowing an inert gas, such as
nitrogen gas, to flow through the reaction system, and the reaction
is satisfactorily fast such that it generally does not need such
inert gas. Further, an inert solvent can be used in the
reaction.
[0050] With respect to the stage in which a dialkyl carbonate is
produced from the alkyl carbamate, the reaction is slightly slow,
and hence a preferred reaction temperature is 180 to 260.degree. C.
The reaction pressure is preferably atmospheric pressure to about 3
MPa. Also in this reaction, ammonia is formed and therefore, by
providing the system with, for example, a pressure control valve,
the reaction may be conducted while appropriately removing ammonia
from the system so as to maintain the inside of the system at a
predetermined pressure. For selectively removing only ammonia from
the system, it is preferred that the reactor is provided with a
distillation column at the upper portion thereof. The reaction time
is about 1 to 20 hours. If necessary, the reaction can be performed
while allowing an inert gas, such as nitrogen gas, to flow through
the reaction system for facilitating the removal of ammonia.
[0051] The above-mentioned reactions can be conducted either in the
same reactor or in separate reactors, and, in both cases, it is
preferred that the same catalyst is used in the reactions. With
respect to the catalyst used in the reactions, various catalysts
are described in, for example, Japanese Unexamined Patent
Publication Nos. Sho 55-102542, Sho 57-26645, and Sho 57-175147,
and any of the catalysts described can be used in the present
invention. Of these, especially, an oxide, a hydroxide, a halide,
an inorganic salt, an organic acid salt, an alkoxide, or an
alkylalkoxide of at least one metal selected from the group
consisting of zinc, magnesium, lead, copper, tin, and titanium is
preferably used. Specific examples thereof include zinc oxide,
magnesium oxide, lead acetate, copper acetate, dibutyltin oxide,
and tetrabutoxytitanium. Further, organic amines, such as
1,4-diazabicyclo[2.2.2]octane and 1,8-diazabicyclo[5.4.0]undecene,
can be used.
[0052] The alkyl alcohol of the formula (1) is used in an amount of
about 0.5 to 10 mol, relative to 1 mol of urea. The amount of the
catalyst is preferably 0.1 to 20 mol %, based on 1 mol of urea. In
this reaction, a preferred alcohol is an alkyl alcohol having 3 or
more carbon atoms. An alkyl alcohol having less than 3 carbon atoms
disadvantageously lowers the yield and increases the pressure
during the reaction.
[0053] After completion of the reaction, a first reaction mixture
containing a dialkyl carbonate can be obtained. The first reaction
mixture can further contain, for example, the unreacted alkyl
alcohol, an alkyl carbamate which is an intermediate, and the
catalyst. Before subjected to the second step, at least part of the
unreacted alkyl alcohol, alkyl carbamate as an intermediate, and
catalyst may be removed from the first reaction mixture by
distillation. The separated alkyl alcohol, alkyl carbamate, and
catalyst can be reused in the reaction.
[0054] (Second Step)
[0055] In the second step, a reaction of the dialkyl carbonate in
the first reaction mixture with an aromatic hydroxy compound is
performed to yield a second reaction mixture containing an
alkylaryl carbonate. The aromatic hydroxy compound used in the
second step is represented by the following formula (4):
Ar--OH (4)
wherein Ar is as defined above. Examples of the aromatic hydroxy
compounds include phenol, p-chlorophenol, 2,4-dichlorophenol,
o-cresol, m-cresol, p-cresol, 2,4-dimethylphenol,
3,4-dimethylphenol, 3,5-dimethylphenol, o-ethylphenol,
m-ethylphenol, p-ethylphenol, p-n-propylphenol, p-isopropylphenol,
p-n-butylphenol, p-isobutylphenol, p-t-butylphenol,
4-hydroxyanisole, p-phenylphenol, and p-phenoxyphenol.
[0056] Specifically, in the second step, the dialkyl carbonate of
the formula (3) is reacted with the aromatic hydroxy compound of
the formula (4) to yield an alkylaryl carbonate of the following
formula (5):
ArO--CO--OR (5)
wherein Ar and R are as defined above. This reaction is conducted
at a reaction temperature of about 160 to 250.degree. C. under a
pressure of about 0.01 to 1 MPa. Further, this reaction is an
equilibrium reaction, and therefore it is preferred to withdraw the
by-produced alkyl alcohol to advance the reaction. The reaction may
be conducted either in a reactor provided with a distillation
column at the upper portion thereof, or in a reactive distillation
column.
[0057] When the second step is performed using a reactive
distillation column, preferred is a distillation column which has
the number of plates of 3 or more, including a condenser plate and
a reboiler plate, and which enables continuous distillation. For
example, any plate column using a bubble cap tray, a sieve tray, or
a valve tray, or any packed column which is packed with a packing,
such as Sulzer laboratory packing, Sulzer packing, Mellapak, Dixon
packing, or Rasching ring, can be used. Of these, a plate column is
more preferably used. The number of plates means the number of
actual plates in the case of a plate column, and means the number
of theoretical plates in the case of a packed column.
[0058] For example, more preferred is a method in which, while
continuously feeding the dialkyl carbonate, aromatic hydroxy
compound, and catalyst to the highest plate of the distillation
column, the by-produced alkyl alcohol is continuously withdrawn
from the top of the column and the alkylaryl carbonate is
continuously withdrawn from the bottom of the column. The reaction
time is about 1 to 10 hours. The reaction can be performed while
allowing an inert gas, such as nitrogen gas, to flow through the
reaction system, but generally, the reaction does not need such
inert gas.
[0059] With respect to a preferred catalyst in this reaction, any
catalyst generally known as a transesterification catalyst can be
used, but, particularly, an alkoxide, an aryloxide, an
alkyl-substituted oxide, or an acetylacetonato of a metal selected
from titanium, aluminum, gallium, tin, and yttrium, or an adduct of
the above compound and another compound is preferably used.
[0060] Among the above catalysts, a titanium compound of the
following formula:
Ti(OX).sub.4, or
Ti(OX).sub.4.XOH
wherein X represents an alkyl group having 3 to 6 carbon atoms, or
aryl group or an adduct thereof is especially preferably used.
[0061] Examples of the catalysts represented by the above formula
include titanium tetrapropoxide, titanium tetrabutoxide, titanium
tetraamyloxide, titanium tetrahexyloxide, titanium tetraphenoxide,
and titanium tetra(4-methylphenoxide) (including their
isomers).
[0062] Alternatively, with respect to the catalyst, a tin compound
of the following formula:
Y.sup.1.sub.2SnO,
Y.sup.1.sub.2Sn(OY.sup.2).sub.2, or
Sn(OY.sup.2).sub.4
wherein Y.sup.1 represents an alkyl group having 1 to 10 carbon
atoms, and Y.sup.2 represents an alkyl group having 3 to 6 carbon
atoms is preferably used.
[0063] Examples of the catalysts represented by the above formula
include diethyltin oxide, dipropyltin oxide, dibutyltin oxide,
diamyltin oxide, dioctyltin oxide, dibutyldibutoxytin,
diethyldiamyloxytin, tetrabutoxytin, and tetraisoamyloxytin
(including their isomers). Alternatively, a compound which is
capable of being transformed into the above compound under the
reaction conditions can be used.
[0064] In this reaction, the aromatic hydroxy compound of the
formula (4) is used in an amount of about 0.2 to 10 mol, relative
to 1 mol of the dialkyl carbonate of the formula (3), more
preferably in an amount about 1 to 5 times the mole of the dialkyl
carbonate. The amount of the catalyst is preferably 0.01 to 10 mol
%, based on 1 mol of the dialkyl carbonate of the formula (3).
[0065] After completion of the reaction, a second reaction mixture
containing an alkylaryl carbonate can be obtained. In this
reaction, generally, an alkylaryl carbonate as well as a diaryl
carbonate are likely to be formed. Accordingly, the second reaction
mixture can further contain, for example, the diaryl carbonate,
by-produced alkyl alcohol, and catalyst. After completion of the
second step, the alkylaryl carbonate may be separated from the
second reaction mixture by distillation, but it is preferred that
the second reaction mixture as such is subjected to the third
step.
[0066] (Third Step)
[0067] In the third step, the alkylaryl carbonate is subjected to
disproportionation to yield a disproportionation reaction mixture
containing a diaryl carbonate and the compound of the formula (I)
in an amount of 1,000 ppm by mass or more. Specifically, in the
third step, the alkylaryl carbonate of the formula (5) is subjected
to disproportionation to yield a third reaction mixture containing
a diaryl carbonate of the following formula (6):
ArO--CO--OAr (6)
wherein Ar is as defined above and the compound of the formula (I)
in an amount of 1,000 ppm by mass or more. This reaction is
conducted at a reaction temperature of about 160 to 250.degree. C.
under a pressure of about 0.01 to 1 MPa. Further, this reaction is
an equilibrium reaction, and therefore it is preferred to withdraw
the by-produced dialkyl carbonate to advance the reaction. The
reaction may be conducted either in a reactor provided with a
distillation column at the upper portion thereof, or in a reactive
distillation column.
[0068] When the third step is performed using a reactive
distillation column, like the second step, preferred is a
distillation column which has the number of plates of 3 or more,
including a condenser plate and a reboiler plate, and which enables
continuous distillation. Especially, a packed column is more
preferably used. For example, more preferred is a method in which,
while feeding the alkylaryl carbonate to the side portion of the
distillation column, the by-produced dialkyl carbonate is
continuously withdrawn from the top of the column, and the third
reaction mixture containing the diaryl carbonate and the compound
of the formula (I) is continuously withdrawn from the bottom of the
column. The reaction time is about 1 to 10 hours. The reaction can
be performed while allowing an inert gas, such as nitrogen gas, to
flow through the reaction system, but generally, the reaction does
not need such inert gas.
[0069] In this reaction, if necessary, a transesterification
catalyst is used. The examples and amount of the
transesterification catalyst are the same as those mentioned above
in connection with the second step.
[0070] (Fourth Step)
[0071] In the fourth step, the third reaction mixture obtained in
the third step is purified. The third reaction mixture generally
can contain the diaryl carbonate and the compound of the formula
(I) as well as, for example, the unreacted alkylaryl carbonate and
catalyst. The purification is preferably performed using a
distillation column.
[0072] For example, the purification of the third reaction mixture
comprises a distillation step of obtaining the diaryl carbonate
containing the compound of the formula (I) in an amount of less
than 1,000 ppm by mass from the top of the distillation column and
obtaining a mixture having concentrated the compound of the formula
(I) and the like from the bottom of the column, wherein the
distillation step is conducted under conditions such (a) that the
pressure at the top of the distillation column is 0.01 to 10 kPa,
and (b) that the reflux ratio at the top of the distillation column
is 0.5 to 20, preferably 2 to 20, further preferably 4 to 20. When
the reflux ratio at the top of the column is less than 2, it is
likely that the content of the compound of the formula (I) in the
diaryl carbonate is 1,000 ppm by mass or more. On the other hand,
when the reflux ratio is more than 20, the efficiency of the
purification is likely to be reduced. The distillation temperature
is generally 100 to 300.degree. C., preferably 120 to 280.degree.
C.
[0073] The fourth step may comprise the separation/removal step for
the catalyst as a part of the purification step. The
separation/removal step for the catalyst is preferably performed
before the distillation step. For example, the separation/removal
step can be performed by continuously feeding the third reaction
mixture to a catalyst separation column (distillation column) so as
to subject the mixture to flash distillation. The alkylaryl
carbonate, diaryl carbonate, and the compound of the formula (I)
are continuously withdrawn from the top of the catalyst separation
column. The catalyst and the diaryl carbonate in a small amount are
continuously withdrawn from the bottom of the column. The liquid
withdrawn from the top of the column can be used in the
distillation step as the third reaction mixture. Alternatively, the
liquid withdrawn from the top of the column may be subjected to the
below-mentioned recovery step for the alkylaryl carbonate, and then
used in the distillation step as the third reaction mixture. The
liquid withdrawn from the bottom of the column can be brought back
to the second step and/or third step and reused as a catalyst.
[0074] The flash distillation is performed at a temperature in the
range of from 100 to 300.degree. C. under a pressure in the range
of from 0.001 to 0.1 MPa.
[0075] Further, the fourth step may comprise the recovery step for
the alkylaryl carbonate as a part of the purification step. The
recovery step is preferably performed before the distillation step
and after the separation/removal step for the catalyst. For
example, the liquid withdrawn from the top of the catalyst
separation column may be continuously fed to an alkylaryl carbonate
recovery column (distillation column) to separate low-boiling point
components including the alkylaryl carbonate. The diaryl carbonate
and the compound of the formula (I) are continuously withdrawn from
the bottom of the column, and the alkylaryl carbonate is
continuously withdrawn from the top of the column. The liquid
withdrawn from the bottom of the column can be used in the
distillation step as the third reaction mixture. The liquid
withdrawn from the top of the column can be brought back to the
third step and reused as a raw material.
[0076] In the recovery step for the alkylaryl carbonate, the
distillation temperature is generally 100 to 300.degree. C.,
preferably 120 to 280.degree. C. The pressure is preferably 0.001
to 0.1 MPa.
[0077] (Fifth Step/Sixth Step)
[0078] The production method of the present invention may further
comprise, as a fifth step, the step of cooling the compound of the
formula (I), which is gradually concentrated and built up on the
bottom of the column while performing the fourth step, to any
temperature in the range of from 80 to 230.degree. C., preferably
82 to 150.degree. C., more preferably 82 to 100.degree. C., and
filtering off the compound. The temperature may be selected
according to the solubility of the compound of the formula (I) in a
diaryl carbonate for reference, for example, the solubility of BOD
in DPC shown in FIG. 1. By virtue of this, the compound of the
formula (I) built up on the bottom of the column can be efficiently
removed. With respect to the method for the filtration, there is no
particular limitation, and a general method may be used. However, a
method using, for example, natural filtration, filtration under
reduced pressure, filtration under pressure, or centrifugal
filtration is preferred. With respect to the filter medium, there
is no particular limitation, and a general filter medium can be
used. However, a filter medium made of a plastic fiber, such as
polypropylene or Teflon (registered trademark), and a filter medium
made of a metal, such as a stainless steel fiber, are preferred
from the viewpoint of being free of a disadvantage, such as falling
of fiber.
[0079] Further, the filtrate obtained in the fifth step can be
brought back to the fourth step, for example, brought as the third
reaction mixture back to any one of the separation/removal step for
the catalyst, the recovery step for the alkylaryl carbonate, and
the distillation step in the fourth step. The production method of
the present invention may comprise such a recycling step as a sixth
step.
[0080] In each of the steps in the production method of the present
invention, the reaction can be conducted in the presence of an
inert solvent, in the presence of an inert gas, and/or under a
pressure using an inert gas. Needless to say, it is preferred that
the individual raw materials used in the present invention have
high purity. Specifically, the purity is preferably 95 to 100%.
Further, the purity of the dialkyl carbonate which is an
intermediate is preferably 90 to 100%.
[0081] The continuous production method of the present invention
can optionally comprise a known step in addition to the
above-mentioned steps. For example, the catalyst separation step
described in Japanese Unexamined Patent Publication No. 2004-323384
may be provided between the transesterification step and the
disproportionation step so that a liquid containing most of the
alkylaryl carbonate and a liquid containing the catalyst are
separated from each other, feeding the liquid containing the
alkylaryl carbonate to the disproportionation step.
[0082] <Method for Producing an Aromatic Polycarbonate
Resin>
[0083] The present invention is also directed to a method for
producing an aromatic polycarbonate resin, wherein the method
comprises performing melt polycondensation in the presence of a
transesterification catalyst using the diaryl carbonate of the
present invention and an aromatic dihydroxy compound. The method
for producing an aromatic polycarbonate resin in accordance with a
melt polymerization method is known, and the diaryl carbonate of
the present invention can be used in such a known method.
[0084] As examples of the aromatic dihydroxy compounds used in the
method for producing an aromatic polycarbonate resin of the present
invention, there can be mentioned compounds of the following
general formula (II).
##STR00005##
[0085] In the general formula (II), each of the two phenylene
groups may be independently a p-phenylene group, a m-phenylene
group, or an o-phenylene group. However, both the two phenylene
groups are preferably a p-phenylene group.
[0086] In the general formula (II), each of R.sup.21 and R.sup.22
is independently a halogen atom, a nitro group, an amino group, an
alkyl group, an alkoxy group, an aryl group, or an aryloxy group.
Specific preferred examples of R.sup.21 and R.sup.22 include
fluorine, an amino group, a methoxy group, a methyl group, and a
phenyl group.
[0087] Each of p and q independently represents an integer of 0 to
4, preferably an integer of 0 to 2. Z represents a single bond or a
divalent group selected from the group of linking groups (III)
shown below. In the group of linking groups (III), each of R.sup.33
and R.sup.34 independently represents a hydrogen atom, an alkyl
group, or an aryl group, or R.sup.33 and R.sup.34 together form an
aliphatic ring.
##STR00006##
[0088] Specific examples of the aromatic dihydroxy compounds
include bis(4-hydroxyphenyl)methane,
1,1-bis(4-hydroxyphenyl)ethane, 1,2-bis(4-hydroxyphenyl)ethane,
2,2-bis(4-hydroxyphenyl)propane,
2,2-bis(4-hydroxy-3-isopropylphenyl)propane,
2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane,
2,2-bis(3-t-butyl-4-hydroxyphenyl)propane,
2,2-bis(3-bromo-4-hydroxyphenyl)propane,
bis(4-hydroxyphenyl)phenylmethane,
1,1-bis(4-hydroxyphenyl)-1-phenylethane,
bis(4-hydroxyphenyl)diphenylmethane,
2,2-bis(4-hydroxy-3-methylphenyl)propane,
1,1-bis(4-hydroxy-3-t-butylphenyl)propane,
2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,
1,1-bis(3-cyclohexyl-4-hydroxyphenyl)cyclohexane,
2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane,
2,2-bis(4-hydroxy-3-phenylphenyl)propane,
2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane,
2,2-bis(4-hydroxy-3-bromophenyl)propane,
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane,
1,1-bis(4-hydroxyphenyl)cyclopentane,
1,1-bis(4-hydroxyphenyl)cyclohexane,
2,2-bis(4-hydroxy-3-methoxyphenyl)propane,
1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane,
4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxybiphenyl,
9,9-bis(4-hydroxyphenyl)fluorene,
9,9-bis(4-hydroxy-3-methylphenyl)fluorene,
1,1-bis(4-hydroxyphenyl)cyclohexane,
1,1-bis(4-hydroxyphenyl)cyclopentane,
4,4'-dihydroxy-3,3'-dimethylphenyl ether, 4,4'-dihydroxyphenyl
sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide,
4,4'-dihydroxydiphenyl sulfoxide,
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide,
4,4'-dihydroxydiphenyl sulfone,
4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone,
2,2'-diphenyl-4,4'-dihydroxydiphenyl sulfonyl,
2,2'-dimethyl-4,4'-dihydroxydiphenyl sulfonyl,
1,3-bis{2-(4-hydroxyphenyl)propyl}benzene,
1,4-bis{2-(4-hydroxyphenyl)propyl}benzene,
1,4-bis(4-hydroxyphenyl)cyclohexane,
1,3-bis(4-hydroxyphenyl)cyclohexane,
4,8-bis(4-hydroxyphenyl)tricyclo[5.2.1.0.sup.2,6]decane,
4,4'-(1,3-adamantanediyl)diphenol, and
1,3-bis(4-hydroxyphenyl)-5,7-dimethyladamantane.
[0089] Of these, 2,2-bis(4-hydroxyphenyl)propane (hereinafter,
frequently referred to as "bisphenol A" or "BPA") is more preferred
for the reasons that, for example, BPA has high stability, and
further BPA having impurities reduced is easily available. Two or
more types of the above-mentioned aromatic dihydroxy compounds may
be used in combination if necessary.
[0090] The diaryl carbonate used in the method for producing an
aromatic polycarbonate resin of the present invention is
specifically a diaryl carbonate which is represented by the
following formula (6):
ArO--CO--OAr (6)
wherein Ar is as defined above, and which contains a compound of
the following formula (I):
##STR00007##
wherein R.sup.1 is as defined above in an amount of less than 1,000
ppm by mass.
[0091] As a specific example of the diaryl carbonate, there can be
mentioned diphenyl carbonate which contains the compound of the
formula (I) wherein R.sup.1 is a hydrogen atom
(2H-1,3-benzoxazine-2,4(3H)-dione) in an amount of less than 1,000
ppm by mass.
[0092] In the method for producing an aromatic polycarbonate resin,
the diaryl carbonate may be used in an excess amount with respect
to the amount of the aromatic dihydroxy compound.
[0093] In the method for producing an aromatic polycarbonate resin,
the polycondensation reaction of the aromatic dihydroxy compound
and diaryl carbonate is conducted in the presence of a catalyst.
With respect to the catalyst, a transesterification catalyst, such
as a basic compound catalyst used as a catalyst for general
polycarbonate production, can be used.
[0094] The catalyst is preferably at least one member selected from
the group consisting of an alkali metal compound and an alkaline
earth metal compound. At least one member selected from the group
consisting of cesium carbonate, sodium hydrogencarbonate, sodium
tetraphenylborate, disodium phenylphosphate, and potassium
carbonate is more preferably used, and at least one of cesium
carbonate and potassium carbonate is further preferably used. The
catalysts can be used individually or in combination.
[0095] The catalyst may be used in an arbitrary amount, for
example, in a ratio of 1.times.10.sup.-6 mol or less, relative to 1
mol of (the total of) the aromatic dihydroxy compound(s).
[0096] It is preferred that the method for producing an aromatic
polycarbonate resin is performed in the presence of a promoter as
well as a catalyst (preferably, at least one member selected from
the group consisting of an alkali metal compound and an alkaline
earth metal compound). By using a promoter, it is possible to more
efficiently produce an aromatic polycarbonate resin.
[0097] With respect to the promoter, a nitrogen-containing compound
for use as a transesterification catalyst is preferably used.
Details of the nitrogen-containing compound are as mentioned above.
With respect to the promoter, specifically, at least one member
selected from the group consisting of quaternary ammonium
hydroxides is preferably used, at least one member selected from
the group consisting of tetraalkylammonium hydroxides is more
preferably used, and tetramethylammonium hydroxide is further
preferably used.
[0098] With respect to the amount of the promoter used, the
promoter may be used in an arbitrary amount, preferably, for
example, 1.times.10.sup.-3 mol or less, relative to 1 mol of (the
total of) the aromatic dihydroxy compound(s).
[0099] In the method for producing an aromatic polycarbonate resin,
it is preferred that the aromatic dihydroxy compound and diaryl
carbonate, which are main raw materials, are subjected to
polycondensation reaction in the presence of a catalyst in a
polycondensation reactor to produce an aromatic polycarbonate
resin. This polycondensation reaction is a melt polycondensation
reaction based on a transesterification reaction.
[0100] With respect to the polycondensation reactor used for
practicing the method for producing an aromatic polycarbonate
resin, one or two or more reactors are used. When two or more
reactors are used, the reactors may be connected in series. The
polycondensation reactor may be either of a vertical type or of a
horizontal type.
[0101] Each polycondensation reactor can be provided with an
agitation apparatus, such as a conventionally known agitating
blade. Specific examples of agitating blades include an anchor
agitator blade, a Maxblend impeller, a double helical ribbon blade,
a lattice blade, and a spectacle-shaped blade.
[0102] It is preferred that the reaction conditions in the
polycondensation reactor are set so that the temperature becomes
higher, the degree of vacuum becomes higher, and the stirring speed
becomes lower as the polycondensation reaction proceeds. It is
preferred that the liquid level in each reactor is controlled so
that the average residence time in each reactor becomes about 30 to
120 minutes during the polycondensation reaction. Further, in each
reactor, phenol which is by-produced concurrently with the melt
polycondensation reaction may be distilled off from the system
through a distillate tube provided in each reactor.
[0103] In the method for producing an aromatic polycarbonate resin,
the degree of vacuum is preferably 1 Pa to 13.3 kPa, and the inner
temperature in the reactor is preferably 140 to 300.degree. C.
EXAMPLES
[0104] Hereinbelow, the present invention will be described in more
detail with reference to the following Examples, which should not
be construed as limiting the scope of the present invention.
[0105] (Measurement of a BOD Concentration)
[0106] Each of the samples (BOD-containing DPC) obtained in
Examples 1 to 10 was dissolved in acetone, and heptylbenzene as an
internal standard material was added to the resultant solution, and
subjected to quantitative determination by means of a gas
chromatography analysis apparatus under the below-shown conditions
for measurement. Substantially the same procedure as mentioned
above was repeated to prepare sample solutions having respective
known concentrations, and a calibration curve was prepared using
the prepared solutions, and used in an analysis for a BOD
concentration in DPC.
<Conditions for Measurement>
[0107] Measuring apparatus: Shimadzu GC-2014
Detector: FID
[0108] Column: GL Sciences Inc. TC-17 (0.30 m.times.0.25 mm I.D.),
Column temperature: 70.degree. C. (5 min)-12.degree.
C./min-190.degree. C. (5 min)-12.degree. C./min-250.degree. C. (30
min) Injection temperature: 250.degree. C. Detection temperature:
260.degree. C. Inlet pressure: 123.8 kPa Column flow rate: 1.53
ml/min Linear velocity: 35.5 cm/s Total flow rate: 81.9 ml/min
Injection mode: SPLIT Control mode: Linear velocity
Carrier gas: He
Examples 1 to 6 and Comparative Examples 1 to 4
(Dibutyl Carbonate (DBC) Synthesis Step)
[0109] Using four continuous reaction vessels each equipped with a
reflux condenser and a stirrer, urea, butanol (BuOH), diphenyl
ether (DPE), and dibutyltin oxide (catalyst) in a [1:2:4:0.05]
molar ratio were individually continuously fed at 126 kg/h to the
first vessel, and a reaction was conducted under conditions such
that the reaction mixture temperatures in the respective vessels
became as follows: the first vessel: 170.degree. C.; the second
vessel: 180.degree. C.; the third vessel: 190.degree. C., and the
fourth vessel: 200.degree. C., and the average residence time in
each vessel became 2 hours while withdrawing the formed ammonia
from the upper portion of the reflux condenser, so that a liquid
containing DBC and butyl carbamate (BCM) was continuously obtained
from the fourth vessel.
[0110] The obtained liquid was subjected to distillation in a
catalyst separation column, so that a liquid comprised mainly of
DPE and the catalyst was first withdrawn from the bottom of the
column, and a liquid containing a part of DPE, DBC, BCM, and BuOH
was withdrawn from the top of the column.
[0111] Then, the liquid withdrawn from the top of the catalyst
separation column was subjected to distillation in a BuOH
separation column, so that BuOH was withdrawn from the top of the
column and a liquid containing DPE, DBC, and BCM was withdrawn from
the bottom of the column.
[0112] Further, phenol (PhOH) was added to the liquid withdrawn
from the bottom of the butanol separation column, wherein the
amount of the phenol added is twice the mole of the DBC contained
in the withdrawn liquid, and the resultant mixture was subjected to
distillation in a BCM separation column, so that a liquid
containing: DBC: 48.0% by mass; PhOH: 51.9% by mass; and BCM: 0.1%
by mass was obtained from the top of the column.
[0113] (Transesterification Step by Reactive Distillation)
[0114] 0.4 Part by mass of titanium tetrabutoxide
(transesterification catalyst) was added to the liquid containing:
DBC: 48.0% by mass; PhOH: 51.9% by mass; and BCM: 0.1% by mass, and
the resultant mixture was continuously fed to the highest plate of
a reactive distillation column for transesterification.
[0115] In this instance, vapor containing BuOH formed in the
transesterification reaction was continuously withdrawn from the
top of the reactive distillation column for transesterification,
and, meanwhile, a liquid containing butylphenyl carbonate (BPC)
formed in the transesterification reaction was continuously
withdrawn from the bottom of the column.
[0116] (Disproportionation Step)
[0117] The liquid withdrawn from the bottom of the reactive
distillation column for transesterification was fed to the middle
portion of a reactive distillation column for disproportionation,
and DBC was continuously withdrawn from the top of the column, and
a mixture containing DPC, the transesterification catalyst, BPC,
and BOD was continuously withdrawn from the bottom of the
column.
[0118] (Purification Step)
<Catalyst Separation Step and BPC Recovery Step>
[0119] The reaction mixture obtained from the bottom of the column
in the disproportionation step was first subjected to distillation
in a catalyst separation column, and the catalyst and a part of DPC
were continuously withdrawn from the bottom of the column, and a
liquid containing mainly DPC and BPC was withdrawn from the top of
the column.
[0120] Then, the liquid withdrawn from the top of the catalyst
separation column was fed to the middle portion of a BPC separation
column, so that a liquid comprised mainly of BPC was obtained from
the top of the column and a mixture containing DPC and BOD (DPC:
99.49% by mass; 2H-1,3-benzoxazine-2,4(3H)-dione (BOD): 0.51% by
mass) was obtained from the bottom of the column.
[0121] <Distillation Step>
[0122] The mixture obtained from the bottom of the BPC separation
column was fed to the 4th plate of a distillation column packed
with Sulzer packing, in which the number of theoretical plates was
8, the column bottom temperature was 188.5.degree. C., and the
column top pressure was 2 kPa, so that the mixture was subjected to
distillation with different reflux ratios, obtaining DPC from the
top of the column. The BOD concentration in the obtained DPC
(column top DPC) is shown in Table 1.
TABLE-US-00001 TABLE 1 Compar- Compar- Compar- Compar- ative ative
ative ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-
Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 1 ple 2 ple 3 ple 4
DPC Feed rate kg/h 15 15 15 15 14 20 30 40 15 15 Purification
Column top KPaA 2.9 2.9 2.9 2.9 2.9 2.8 3 2.9 2.9 2.9 pressure
Reflux ratio R/D 20 15 9 4 3 2 1 0.5 0.1 0 BOD LC ppm 0.3 3 30 300
600 900 1300 1700 3000 5100 Concentration Composition in column top
DPC
Examples 7 to 30
<Precipitation Step>
[0123] The distillation step in each Example was performed until
the compound of the formula (I) in the liquid in the vessel was
built up in such a concentration that the compound was precipitated
when the temperature at the bottom of the column was reduced to
188.5.degree. C. or lower. The resultant liquid in the vessel was
withdrawn and then cooled so that the compound of the formula (I)
was precipitated, followed by filtration under reduced pressure
using No. 5C filter paper having a diameter of 330 mm, manufactured
by Advantech Toyo Kaisha, Ltd., recovering a filtrate. The
concentrations of the compound of the formula (I) and the
precipitation conditions in the respective procedures are shown in
Table 2. The solubility of BOD in DPC was measured and found to be
as shown in FIG. 1.
TABLE-US-00002 TABLE 2 Example 7 8 9 10 11 12 13 14 15 16 17 18
Example for distillation step 1 2 3 4 5 6 1 2 3 4 5 6 BOD
Concentra- GC wt % 25.9 25.5 24.8 23.3 22.6 21.4 25.9 25.5 24.8
23.3 22.6 21.4 tion in column Compo- bottom DPC sition
Precipitation .degree. C. 82 82 82 82 82 82 100 100 100 100 100 100
temperature BOD Concentra- GC ppm 4119 4115 4116 2120 4122 4118
11631 11635 11636 11632 11635 11634 tion in filtrate Compo- DPC
sition Example 19 20 21 22 23 24 25 26 27 28 29 30 Example for
distillation step 1 2 3 4 5 6 1 2 3 4 5 6 BOD Concentra- GC wt %
25.9 25.5 24.8 23.3 22.6 21.4 25.9 25.5 24.8 23.3 22.6 21.4 tion in
column Compo- bottom DPC sition Precipitation .degree. C. 120 120
120 120 120 120 150 150 150 150 150 150 temperature BOD Concentra-
GC ppm 27899 27895 27903 27899 27897 27902 85595 85599 85598 85596
85599 85602 tion in filtrate Compo- DPC sition
Example 31
<Recycling Step>
[0124] The catalyst separation step and BPC recovery step in the
purification step were performed in accordance with the same
procedure as in Example 2. Then, the filtrate obtained in the
precipitation step in Example 20 was added to the mixture obtained
from the bottom of the BPC separation column in the BPC recovery
step, and the resultant mixture was subjected to the distillation
step in accordance with the same procedure as in Example 2. The BOD
concentration (GC composition) of the obtained column top DPC was
equivalent to the BOD concentration (GC composition) in Example 2
which includes no recycling.
Examples 32 to 36 and Comparative Example 5
(Evaluation of Polycarbonate Polymerization Activity)
[0125] In Examples 32 to 36 and Comparative Example 5, with respect
to the DPCs obtained in Examples 1 to 4 and 6 and Comparative
Example 3, polycarbonate (PC) polymerization between each DPC and
bisphenol A (BPA) was evaluated.
[0126] (Raw Materials for Polymerization)
[0127] With respect to DPC, those which are shown in Table 1 above
for Examples 1 to 4 and 6 and Comparative Example 3 were used, and,
with respect to BPA, one which is manufactured by Nippon Steel
& Sumikin Chemical Co., Ltd. was used.
[0128] (Polymerization Catalyst)
[0129] 0.15 g of cesium carbonate, manufactured by Wako Pure
Chemical Industries, Ltd., was accurately weighed, and dissolved in
distilled water using a 100 mL measuring flask to obtain a 0.005
mol/L aqueous solution of cesium carbonate.
[0130] (Analysis Method for Molecular Weight)
[0131] With respect to the obtained resin, an analysis of a
molecular weight was conducted using high-performance GPC apparatus
HLC-8320 GPC, manufactured by Tosoh Corp., which is equipped with
three columns for ultra-high performance semi-micro SEC, TSKgel
SuperMultipore (registered trademark) HZ-M, manufactured by Tosoh
Corp., and using a chloroform solvent (for HPLC), manufactured by
Wako Pure Chemical Industries, Ltd., under conditions such that the
sample concentration was 0.2 w/v %, the flow rate was 0.350 mL/min,
and the amount of the sample per injection was 10 .mu.L. A
calibration curve was prepared using standard polystyrene kit
PStQuick (registered trademark) MP-M, manufactured by Tosoh
Corp.
[0132] (Measurement of a Terminal OH Amount)
[0133] The measurement of a terminal OH amount was performed using
Cryo NMR, manufactured by Bruker Corporation. 0.05 g of a sample
was dissolved in 1 mL of a 0.05 wt % TMS-added, deuterated
chloroform solvent, and subjected to measurement of .sup.1H-NMR at
a standard frequency of 600 MHz. In the obtained NMR spectrum, the
integrated area of a peak ascribed to a phenyl group and a
phenylene group appearing at around 7 to 8 ppm was taken as 100,
and a ratio of the integrated area of a peak ascribed to a hydroxyl
group appearing at around 4.7 ppm to the above integrated area was
calculated, and thus a terminal amount was determined from the
ratio.
[0134] (Analysis for a Yellow Index(YI) Value)
[0135] A YI value was measured using colorimeter SE2000,
manufactured by Nippon Denshoku Industries Co., Ltd., with respect
to 6 g of a sample which was dissolved in 60 mL of a
dichloromethane solvent, manufactured by Wako Pure Chemical
Industries, Ltd.
[0136] (Polymerization Apparatus)
[0137] A 300 mL four-neck glass flask was used as a polymerization
apparatus, wherein the glass flask has connected thereto a
distillation portion made of glass having a connecting tube, an air
condenser, an alcohol thermometer and a receiver, and a stirrer for
flask having a stainless steel stirring rod and a Teflon
(registered trademark) agitating blade. A nitrogen gas introducing
tube and a rotary pump were connected to the polymerization
apparatus through the connecting tube which connects the receiver
and air condenser, enabling the pressure in the polymerization
apparatus to be controlled.
[0138] (Procedure for Polymerization)
[0139] 70.0 g of BPA, 69.6 g of DPC (molar ratio of DPC to BPA:
1.06), and 30 .mu.L of a 0.005 mol/L aqueous solution of cesium
carbonate as a catalyst were charged into the polymerization
apparatus.
[0140] Then, for drying the BPA, DPC, and catalyst charged into the
polymerization apparatus, while stirring at 4 rpm using the stirrer
for flask, drying was performed in a vacuum at 27.degree. C. for
one hour. After drying, the pressure in the polymerization
apparatus was increased to 97 kPa using nitrogen gas.
[0141] A point in time when the flask portion of the polymerization
apparatus, which had been dried and increased in the pressure, was
immersed in an oil bath set at 205.degree. C. was regarded as a
start of polymerization, and the raw materials were melted for 5
minutes while stirring at 4 rpm using the stirrer for flask, and
the number of revolutions of the stirrer for flask was increased to
200 rpm, followed by stirring for 5 minutes.
[0142] The pressure in the polymerization apparatus was reduced
from 97 to 27 kPa for 10 minutes while stirring, and a point in
time when the alcohol thermometer of the polymerization apparatus
indicated 100.degree. C. was recorded as a time for the start of
distilling off of phenol by-produced in the reaction of BPA and
DPC.
[0143] From a point in time when the amount of the phenol distilled
off during the reaction reached 30% of the distilled phenol amount
presumed from the amounts of the charged raw materials, the
temperature set for the oil bath and the pressure in the
polymerization apparatus were changed stepwise according to the
distilled phenol amount, and, from a point in time when the
distilled phenol amount reached 90% of the presumed amount of the
phenol distilled, the temperature of the oil bath was increased to
260.degree. C. and the pressure in the polymerization apparatus was
reduced to achieve a vacuum for 10 minutes. In the case where the
BOD content in the DPC was 3,000 ppm by mass, the above-mentioned
procedure did not cause phenol to be distilled off. Therefore, the
temperature set for the oil bath was increased and the pressure in
the polymerization apparatus was reduced so as to cause phenol to
be distilled off.
[0144] After stirring was made in a vacuum at an oil bath
temperature of 260.degree. C. for 1.5 hours, the reaction was
terminated, and the PC in the polymerization apparatus was
recovered. The results shown in Table 3 were obtained according to
the BOD content in the DPC used.
TABLE-US-00003 TABLE 3 Example Example Example Example Example
Comparative 32 33 34 35 36 Example 5 DPC Example 1 Example 2
Example 3 Example 4 Example 6 Comparative Example 3 BOD Content 0.3
ppm 3 ppm 30 ppm 300 ppm 900 ppm 3000 ppm Start of 27 min. 29 min.
31 min. 42 min. 71 min. *1 distilling 30% Distilled 60 min. 60 min.
70 min. 100 min. 180 min. *1 90% Distilled 190 min. 190 min. 200
min. 235 min. 325 min. *1 Mw 31,000 31,000 26,000 22,000 17,000
9,000 Terminal OH 216 ppm 394 ppm 650 ppm 451 ppm 523 ppm 2702 ppm
amount Solution YI -- 1.51 1.52 1.50 1.60 1.81 *1: The temperature
of the oil bath and the pressure in the polymerization apparatus
were changed to cause a phenol to be distilled off.
[0145] In the production of an aromatic polycarbonate resin by a
melt transesterification method, by using a diaryl carbonate
containing the compound of the formula (I) in an amount of less
than 1,000 ppm by mass, the polymerization time can be markedly
reduced and an aromatic polycarbonate resin having suppressed the
terminal OH group amount can be obtained, as compared to those in
the production of an aromatic polycarbonate resin using a diaryl
carbonate produced by a conventional method.
* * * * *