JP2002308979A - Process for producing aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for stably producing an aromatic polycarbonate having a narrow molecular weight distribution and properties excellent in initial color hue. SOLUTION: In the process for producing the aromatic polycarbonate by continuously feeding raw materials comprising an aromatic dihydroxy compound and a carbonic diester into a raw material mixing tank, and continuously feeding the obtained mixture into a polymerization tank where an aromatic polycarbonate is produced by a transesterification method using a transesterification catalyst, (1) set amounts of the transesterification catalyst for one or more unit production times provided by fractionating the whole production time are selected from the range from 0.05 to 5 μmol for 1 mol of the aromatic dihydroxy compound or the carbonic diester, and (2) the actual amount of the transesterification catalyst fed is maintained to a value within each set amount of the transesterification catalyst plus or minus 0.1 μmol for 1 mol of the aromatic dihydroxy compound or the carbonic diester for a time at least 95% of each unit production time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate by a transesterification method between an aromatic dihydroxy compound and a carbonic acid diester.

[0002]

2. Description of the Related Art Aromatic polycarbonate is a resin excellent in various strengths and excellent in transparency, and is used in a wide range of fields. As an industrial production method of this polycarbonate, an interfacial polymerization method in which bisphenol A and phosgene are reacted in a methylene chloride solvent is generally used, but this method requires the use of phosgene and methylene chloride which are industrially difficult to handle. In recent years, a method for producing polycarbonate by transesterification without using these compounds and using an aromatic dihydroxy compound such as bisphenol A and a carbonic diester such as diphenyl carbonate as raw materials has been partially industrialized in recent years. (For example, Japanese Patent Application Laid-Open No. 2-153925, Japanese Patent Publication No. 6-99552).
And JP-A-63-51429.

In order to carry out the transesterification reaction, a transesterification catalyst is generally used. However, if the transesterification catalyst is not used in an appropriate type or amount, the initial hue of the aromatic polycarbonate, the thermal stability upon melting and the resistance to hydrolysis, etc., deteriorate, and the branched structure also increases. was there. In order to solve these problems, various methods have been proposed.

For example, in Japanese Patent Application Laid-Open No. 8-81551, an attempt is made to produce a less colored aromatic polycarbonate resin by using a rare earth element as a transesterification catalyst. There was a disadvantage that there was no. Further, in Japanese Patent No. 2924985, the amount of alkali impurities in the raw material is regulated to 1 ppb or less, and the alkali metal compound is added to the aromatic dihydroxy compound in an amount of 5 × 1 in a total amount in the reaction system per 1 mol of the aromatic dihydroxy compound.
Melt polycondensation in the presence of 0 ^-8 to 8 × 10 ^-7 mol of an alkali metal compound and / or an alkaline earth metal compound to obtain a reaction product having excellent heat stability, hue stability and the like upon melting. Trying to get.

However, even if the amount of alkali impurities in the raw material is precisely controlled and the amount of the transesterification catalyst such as an alkali metal compound is specified in an extremely narrow range, the production of aromatic polycarbonate in the actual production of aromatic polycarbonate is If the catalyst flow rate is not controlled and the catalyst flow rate fluctuates with respect to 1 mole of the dihydroxy compound, the obtained aromatic polycarbonate has a particularly wide molecular weight distribution, deteriorates the hue, and stabilizes a high-quality product. Could not be manufactured.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method for stably producing an aromatic polycarbonate having a narrow molecular weight distribution and excellent quality in initial hue.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above circumstances, and as a result, have found that the amount of transesterification catalyst can be reduced.
It has been found that the control can be performed with extremely high precision, as compared with the conventional method, and the present invention has been completed. That is, the present invention uses an aromatic dihydroxy compound and a carbonic acid diester as raw materials, continuously supplies these raw materials to a raw material mixing tank, continuously supplies the obtained mixture to a polymerization tank, and performs a transesterification method. In producing the aromatic polycarbonate, (1) the set transesterification catalyst amount is set to 0 with respect to 1 mol of the aromatic dihydroxy compound or the carbonic acid diester for each of at least one unit production time provided by fractionating the total production time. And (2) at least 95% of the unit production time, when the actual amount of transesterification catalyst supplied is 1 mol of aromatic dihydroxy compound or diester carbonate. The present invention also relates to a method for producing an aromatic polycarbonate, wherein each of the set transesterification catalyst amounts is maintained at a value within ± 0.1 μmol.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for producing an aromatic polycarbonate of the present invention will be described more specifically.
In the present invention, an aromatic polycarbonate is produced by a transesterification method using an aromatic dihydroxy compound and a carbonic acid diester as raw materials.

Aromatic dihydroxy compound : The aromatic dihydroxy compound which is one of the raw materials of the method of the present invention is a compound represented by the following general formula (1).

[0010]

Embedded image (In the formula, A is a single bond, an optionally substituted carbon atom 1
10 to 10 linear, branched or cyclic divalent hydrocarbon groups, or -O-, -S-, -CO- or -SO ₂
Is a divalent group represented by-, X and Y are a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and p and q are
It is an integer of 0 or 1. Note that X and Y and p and q may be the same or different from each other. Representative aromatic dihydroxy compounds include, for example, bis (4-hydroxydiphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5
-Dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 4,
4-bis (4-hydroxyphenyl) heptane, 1,1
-Bis (4-hydroxyphenyl) cyclohexane,
4,4′-dihydroxybiphenyl, 3,3 ′, 5
5'-tetramethyl-4,4'-dihydroxybiphenyl, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone, etc. Is mentioned. These aromatic dihydroxy compounds can be used alone or in combination of two or more. Among them, 2,2-bis (4
-Hydroxyphenyl) propane (hereinafter abbreviated as "bisphenol A" or "BPA") is preferred.

Carbonic diester : Carbonic diester , another raw material of the present invention, is a compound represented by the following general formula (2).

[0012]

Embedded image (Wherein A ′ has 1 to 10 carbon atoms which may be substituted.
Is a linear, branched or cyclic monovalent hydrocarbon group of
Two A's may be the same or different from each other. Representative examples of the carbonic acid diester include dialkyl carbonates such as substituted diphenyl carbonate represented by diphenyl carbonate and ditolyl carbonate, dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate. These carbonic acid diesters can be used alone or in combination of two or more. Among these, diphenyl carbonate (hereinafter sometimes abbreviated as “DPC”) is particularly preferred.

These diester carbonates are usually used in excess with respect to the aromatic dihydroxy compound. That is, from 1.001 to aromatic dihydroxy compound
It is preferably used in a molar ratio of 1.3, preferably in a molar ratio of 1.02 to 1.2. When the molar ratio is less than 1.001, the terminal hydroxyl groups of the produced aromatic polycarbonate increase, and the thermal stability of the polymer tends to deteriorate. When the molar ratio is more than 1.3,
Under the same conditions, the rate of transesterification decreases, and it tends to be difficult to produce an aromatic polycarbonate having a desired molecular weight.

As a method of supplying the raw material to the raw material mixing tank,
It is preferable that one or both of the aromatic dihydroxy compound and the carbonic acid diester are melted and supplied in the liquid state because the liquid state is easier to maintain high measurement accuracy. When the raw material is supplied in a liquid state, an oval flow meter, a micro motion type flow meter, or the like can be used as the measuring device.

On the other hand, when the raw material is supplied in a solid state, it is preferable to use a material for measuring the weight rather than a device for measuring the volume such as a screw feeder.
A weight feeder such as a belt type or a loss-in-weight type can be used, but a loss-in-weight type is particularly preferable. Transesterification catalyst : When a polycarbonate is produced by a transesterification method, a catalyst is usually used. In the polycarbonate production method of the present invention, the catalyst species is not limited, but generally, an alkali metal compound, an alkaline earth metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound, an amine compound, or the like. Are used. These may be used alone or in combination of two or more.
The amount of the catalyst to be used is 0.05 to 5 μmol, preferably 0.08 to 4 μmol, and more preferably 0.1 to 2 μmol per 1 mol of the aromatic dihydroxy compound or carbonic acid diester.
Used in the molar range.

If the amount of the catalyst used is less than the above-mentioned amount, the polymerization activity required for producing a polycarbonate having a desired molecular weight cannot be obtained. If the amount is more than this amount, the polymer hue deteriorates and the polymer branches. And the fluidity during molding decreases. Examples of the alkali metal compound include inorganic alkali metal compounds such as lithium, sodium, potassium, rubidium, and cesium hydroxides, carbonates, and hydrogen carbonate compounds; and organic compounds such as salts with alcohols, phenols, and organic carboxylic acids. There are alkali metal compounds and the like. Among these alkali metal compounds, cesium compounds are preferable, and cesium carbonate, cesium hydrogencarbonate, and cesium hydroxide are specific examples of the most preferable cesium compounds.

Further, as the alkaline earth metal compound,
There are inorganic alkaline earth metal compounds such as beryllium, calcium, magnesium and strontium hydroxides and carbonates, and organic alkaline earth metal compounds such as salts with alcohols, phenols and organic carboxylic acids.
Examples of the basic boron compound include, for example, tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron, trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron, triethylphenyl boron, tributylbenzyl Boron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, strontium salt, etc. is there.

Examples of the basic phosphorus compound include trivalent phosphorus compounds such as triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, and tributylphosphine; There are quaternary phosphonium salts derived from compounds. Examples of the basic ammonium compound include, for example, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, Triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide,
Examples include tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide, and butyltriphenylammonium hydroxide.

Examples of the amine compound include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine,
2-hydroxypyridine, 2-methoxypyridine, 4-
Methoxypyridine, 2-dimethylaminoimidazole,
Examples include 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.

Of these catalysts, practically, alkali metal compounds are desirable. The transesterification catalyst is used, for example, in the form of a catalyst solution dissolved in a solvent such as water, acetone, alcohol, toluene, phenol, the raw material aromatic dihydroxy compound or carbonic acid diester. In these solvents, water is preferable, and in particular, when an alkali metal compound is used as a catalyst, an aqueous solution is preferable.

Method for Producing Aromatic Polycarbonate : In order to produce the aromatic polycarbonate of the present invention, the above two raw materials are continuously supplied to a raw material mixing tank, and the obtained mixture and a transesterification catalyst are supplied to a polymerization tank. Preferably, it is supplied continuously. At that time, in order to stably produce a polymer having desired physical properties, (1) the set transesterification catalyst amount (hereinafter simply referred to as “ The "set catalyst amount" is defined as 0.1 to 1 mole of the aromatic dihydroxy compound or carbonic acid diester.
(5) at least 95% of the unit production time is determined by the actual amount of transesterification catalyst supplied (hereinafter simply referred to as "actual catalyst amount").
That. ) Must be maintained at a value within ± 0.1 μmol of each set catalyst amount per 1 mol of the aromatic dihydroxy compound or carbonic acid diester.

In the production of an aromatic polycarbonate by a transesterification method, usually, both raw materials supplied to a raw material mixing tank are uniformly stirred and then supplied to a polymerization tank to which a catalyst is added, thereby producing a polymer. You. At this time, in order to keep the amount of the catalyst per mole of the aromatic dihydroxy compound or carbonic acid diester supplied to the polymerization tank, it is preferable to first set the target “set catalyst amount”. This is from 0.05 to 5 per mol of the aromatic dihydroxy compound or carbonic acid diester for the reasons described above.
It is preferred to be selected from within the range of μmol. The set transesterification catalyst amount does not necessarily have to be a constant value throughout the entire production time, but can be set for each of one or more unit production times provided by dividing the entire production time. In addition, the above "total production time" or "unit production time"
The term “corresponds to the supply time of the raw material for stably producing the polymer in the polymerization tank, and does not include the time required for the production of the polymer at the time of instability at the time of startup or at the time of grade switching.

Next, it is preferable to control the relationship between the set amount of catalyst and the actual amount of catalyst supplied to the polymerization tank within a predetermined range over the entire production time. That is, when the total production time is a unit production time of a single fraction, at least 95% of the time is the set catalyst amount ± 0.1 μm per mol of the aromatic dihydroxy compound or carbonic acid diester.
If the total production time is fractionated into a plurality of unit production times and the set catalyst amount is changed, at least 95% of each unit production time must be equal to or less than the set catalyst amount ± The actual amount of catalyst is maintained at a value within 0.1 μmol.
Furthermore, it is preferable to maintain it within ± 0.08 μmol, particularly preferably within ± 0.06 μmol. At each unit production time, the percentage of time that the actual amount of catalyst is maintained at a controlled value is at least 95%
However, it is more preferable that it is at least 99%, and even closer to 100%. When the time is less than 95%, a polymer having a desired molecular weight and a terminal OH group content cannot be stably obtained, the molecular weight distribution is widened, and the polymer hue tends to deteriorate. In addition, if the molecular weight and the amount of terminal hydroxy groups are maintained by changing the production conditions during the polymerization reaction such as polymerization temperature, polymerization time, and degree of reduced pressure, the polymerization operation becomes complicated, and stable production tends to be difficult. is there.

Only by continuing the supply while maintaining the catalyst amount within a very small fluctuation range of ± 0.1 μ,
A complicated polymerization operation can be avoided, and a polymer excellent in various physical properties such as molecular weight distribution, color tone, fluidity, heat resistance and mechanical properties can be stably produced. In particular, the molecular weight distribution tends to be clearly narrower due to the above control compared to the case where no control is performed.

In order to maintain the actual amount of the catalyst within the set amount of the catalyst within ± 0.1 μmol, the measurement accuracy of the flow rate of the catalyst supplied to the polymerization tank should be equal to or higher than the accuracy of the flow rate of the catalyst to be maintained. It is necessary. Otherwise, it is difficult to maintain a constant catalyst flow rate. As a method for supplying the catalyst to the polymerization tank, it is preferable to use an oval flow meter, a micro motion type flow meter, or the like. The supply of the catalyst is not limited to the polymerization tank, but may be a raw material preparation tank.

In order to automatically control the supply of the catalyst, for example, a measured value of the actual catalyst flow rate is continuously input to a computer, and the set catalyst amount and the supply amount of the aromatic dihydroxy compound to the raw material preparation tank described above are input. The calculated catalyst flow rate is compared with the calculated catalyst flow rate. At that time, the measured value of the actual catalyst flow rate,
If it is different from the set catalyst flow rate, this result is
It can be performed by controlling the valve so that the actual catalyst flow rate matches the set catalyst flow rate by adjusting the valve opening and the like to the supply device.

Here, "automatic control of catalyst supply" means that control is performed in the same manner as continuous measurement, even in continuous intermittent measurement, if sufficient consideration is given to optimizing the measurement interval of the actual catalyst flow rate. Although it is possible, to obtain a product of stable quality, the measurement of the actual catalyst flow rate is preferably a continuous automatic measurement. That is, if the catalyst flow rate can be continuously and automatically measured, it is possible to quickly and continuously control the amount of the catalyst supplied to the polymerization tank. As a result, the catalyst flow rate is maintained at a constant set value, and the molecular weight distribution of the polycarbonate is narrow. In addition, a product having various physical properties such as color tone, fluidity, heat resistance, and mechanical properties can be obtained. Further, in the case of continuous control, it is possible to perform an operation to change the control mode at appropriate control intervals.

During the unit production time of a certain set catalyst amount, it is easy to determine how long the actual catalyst amount has been within the set catalyst amount ± 0.1 μmol from the measurement result by the above-mentioned measuring means. Can be determined. In the case of continuous measurement, a cumulative time within a preset catalyst amount of ± 0.1 μmol and a cumulative time deviating from ± 0.1 μmol are obtained from a curve showing the relationship between the actual catalyst amount and the measurement time. Thus, it is determined whether at least 95% of the unit production time at the set catalyst flow rate has been maintained at a value within ± 0.1 μmol. Even if the measurement is not a continuous measurement, it can be determined by a statistical processing method or the like if the measurement is a continuous measurement.

The transesterification is generally preferably carried out continuously in two or more stages, usually in three to seven stages. Specific reaction conditions include a temperature of 150
To 320 ° C., pressure: normal pressure to 1.33 Pa, average residence time: 5 to 150 minutes. In each polymerization tank, in order to more effectively discharge phenol by-produced as the reaction proceeds. Then, a higher temperature and a higher vacuum are set stepwise within the above reaction conditions. In order to prevent the deterioration of the hue and the like of the obtained aromatic polycarbonate, it is preferable to set the temperature as low as possible and the residence time as low as possible.

The apparatus used in the above transesterification reaction may be any of a vertical type, a tube type or a tower type, and a horizontal type. Usually, turbine blades, paddle blades, anchor blades,
Full zone wing (Shinko Pantech Co., Ltd.), Sun Meller wing (Mitsubishi Heavy Industries, Ltd.), Max Blend wing (Sumitomo Heavy Industries, Ltd.), helical ribbon wing, twisted lattice wing (Hitachi, Ltd.) ), A horizontal uniaxial polymerization tank such as a disk type or a cage type, HVR, SCR, N-SCR (manufactured by Mitsubishi Heavy Industries, Ltd.), a vivolac (Sumitomo Heavy Industries, Ltd.) Machine Industry Co., Ltd.
Wings, eyeglass wings, lattice wings (manufactured by Hitachi, Ltd.), or a combination of eyeglass wings and a wing with a polymer feeding function, for example, a wing with a twist or twist and / or an inclined wing. And a horizontal biaxial type polymerization tank equipped with a polymerization tank.

In the aromatic polycarbonate produced by the above method, low molecular weight compounds such as a raw material monomer, a catalyst, an aromatic hydroxy compound by-produced in a transesterification reaction, and an aromatic polycarbonate oligomer usually remain. Among them, the raw material monomer and the aromatic hydroxy compound have a large residual amount and adversely affect physical properties such as heat aging resistance and hydrolysis resistance.

The method for removing them is not particularly limited, and for example, devolatilization may be performed continuously using a vented extruder. At that time, the basic transesterification catalyst remaining in the resin, by adding an acidic compound or a precursor thereof in advance and deactivating it, suppresses side reactions during devolatilization, efficiently starting monomer and Aromatic hydroxy compounds can be removed.

The acidic compound or its precursor to be added is not particularly limited, and any compound can be used as long as it has an effect of neutralizing the basic transesterification catalyst used in the polycondensation reaction. Specifically, hydrochloric acid, nitric acid, boric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, adipic acid, ascorbic acid, aspartic acid, azelaic acid, adenosine phosphate, benzoic acid, Formic acid, valeric acid, citric acid, glycolic acid, glutamic acid, glutaric acid, cinnamic acid, succinic acid, acetic acid, tartaric acid, oxalic acid, p-toluenesulfinic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, nicotinic acid, picrin Acid, picolinic acid,
Bronsted acids such as phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid and maleic acid, and esters thereof. These may be used alone or in combination of two or more. Among these acidic compounds or precursors thereof, sulfonic acid compounds or ester compounds thereof, for example, p-toluenesulfonic acid, methyl p-toluenesulfonate, butyl p-toluenesulfonate and the like are particularly preferable.

The amount of addition of these acidic compounds or their precursors is 0.1 to 50 times, preferably 0.1 to 50 times the amount of neutralization of the basic transesterification catalyst used in the polycondensation reaction.
It is added in a range of 5 to 30 times mol. The timing of adding the acidic compound or its precursor may be any time after the polycondensation reaction, and there is no particular limitation on the addition method, depending on the properties and desired conditions of the acidic compound or its precursor.
Any of a direct addition method, a method of dissolving in a suitable solvent and adding, and a method using a pellet or flake-like master batch may be used.

If necessary, additives such as a stabilizer, an ultraviolet absorber, a release agent, and a coloring agent may be added and kneaded with the resin.

[0036]

The present invention will be described below with reference to examples and comparative examples. Incidentally, the analysis of the obtained aromatic polycarbonate,
The measurement was performed by the following measurement method. (1) Viscosity-average molecular weight (Mv) Using a Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured.
v) was determined.

[0037]

[Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83 (2) Terminal hydroxyl group concentration (ppm) Titanium tetrachloride / acetic acid method (Makromol. Che)
m. 88 215 (1965)).

(3) Molecular weight distribution (Mw / Mn) Measured by gel permeation chromatography (GPC). The measuring device was HLC manufactured by Tosoh Corporation.
-8020 was determined in terms of polystyrene using tetrahydrofuran as an eluent, and Mw / Mn was calculated. (4) Hue (YI) The produced aromatic polycarbonate was treated at 280 ° C. with 100
A press sheet having a thickness of 100 mm x 3 mm was injection molded, and the press sheet was measured for tristimulus values XYZ, which are absolute values of color, using a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.). The YI value which is an index of the degree of yellowness was calculated by the relational expression The larger the YI value, the more colored.

[0039]

## EQU2 ## YI = (100 / Y) × (1.28 × X−1.
06 × Z)

[0040]

Embodiment 1 An embodiment of a method for producing an aromatic polycarbonate will be described with reference to FIG. FIG. 1 is a flow sheet diagram showing one example of the production method of the present invention. In the figure, 1 is a DPC storage tank, 2 is a stirring blade, 3 is a BPA hopper, 4a,
b is a raw material mixing tank, 5 is a DPC flow control valve, 6 is a BPA flow control valve, 7 and 10 are pumps, 8 is a catalyst flow control valve, 9
Is a program controller, 11 is a catalyst storage tank, 12 is a by-product discharge pipe, 13a, b and c are vertical polymerization tanks, 14 is a max blend blade, 15 is a horizontal polymerization tank, and 16 is a lattice blade.

A diphenyl carbonate melt prepared at 120 ° C. in a nitrogen gas atmosphere and bisphenol A powder weighed in a nitrogen gas atmosphere were respectively charged from a DPC storage tank (1) at 208.9 mol / h and a BPA hopper ( 3) to 197.1 mol / h (raw material molar ratio: 1.06
0) weigh with a micro motion type flow meter and a loss-in weight type weight feeder so that
Raw material mixing tank (4a) adjusted to 140 ° C under nitrogen atmosphere
Continuously. Subsequently, the raw material mixture was added to the raw material mixing tank (4b) via the pump (7), and the volume thereof was set to 100 L.
Was supplied continuously to the first vertical stirring polymerization tank (13a).
On the other hand, simultaneously with the start of the supply of the mixture, a 2% by weight aqueous cesium carbonate solution as a catalyst was passed through a catalyst introduction tube.
Continuous supply was started at a flow rate of 0.96 mL / hour (set catalyst amount: 0.3 μmol with respect to 1 mol of bisphenol A).

At this time, the actual catalyst flow rate control is based on the BPA flow rate detected by the BPA flow rate control valve (6) and the set catalyst quantity, and a program controller (9) installed in advance.
The above procedure was performed by calculating the set catalyst flow rate and controlling the opening of the catalyst flow control valve (8) so as to match the catalyst flow rate measured by the catalyst flow control valve (8). The first vertical stirring polymerization tank (13a) equipped with the Max Blend blade (14) is at 220 ° C. under normal pressure and nitrogen atmosphere.
, And so that the average residence time is 60 minutes,
The liquid level was kept constant while controlling the opening of the valve provided in the polymer discharge line at the bottom of the tank.

The polymerization liquid discharged from the bottom of the tank is continuously
Capacity 100 with second and third max blend wings
L vertical stirring polymerization tanks (13b, 13c) and a 150-L horizontal polymerization tank (1) equipped with a fourth lattice blade (16).
It was supplied continuously and sequentially in 5). The reaction conditions in the second to fourth polymerization tanks were set such that the temperature became higher, the vacuum became lower, and the stirring speed became lower as the reaction progressed, as described below.

[0044]

Table 1 Temperature Pressure Stirring speed Second polymerization tank (13b) 220 ° C 1.33 × 10 ⁴ Pa 110 rpm Third polymerization tank (13c) 240 ° C. 2.00 × 10 ³ Pa 75 rpm Fourth polymerization tank (15 ) 260 ° C 66.7 Pa 10 rpm During the reaction, the liquid level was controlled so that the average residence time in the second to fourth polymerization tanks was 60 minutes, and by-products were produced in each polymerization tank. Phenol to the by-product discharge pipe (1
Removed from 2). Under the above conditions, the operation was continued for 1500 hours. The aromatic polycarbonate extracted from the polymer outlet at the bottom of the fourth polymerization tank was introduced into a twin-screw extruder equipped with a three-stage vent in a molten state, and butyl p-toluenesulfonate was converted into polycarbonate. After adding 2.5 ppm, hydrogenating and devolatilizing, the mixture was pelletized.

The viscosity average molecular weight (Mv) of the obtained aromatic polycarbonate was 15,300 and the terminal hydroxyl group concentration was 540 ppm. From the continuous measurement data of the catalyst flow rate actually measured by the measuring device provided in the catalyst flow rate control valve (8), the time within the set catalyst amount ± 0.1 μmol was calculated with respect to 1 mole of the aromatic dihydroxy compound. However, the ratio is 99.4% of the total production time,
The proportion of time within 0.06 μmol is 9% of the total production time.
7.1%. In addition, molecular weight distribution (Mw / Mn)
Was 2.2, and the hue of the press sheet injection-molded at 280 ° C. was 1.4. The evaluation results are shown in Table-1.

[0046]

Example 2 In Example 1, the set raw material molar ratio was set to 1.
040, the catalyst flow rate was 1.6 mL / hour (set catalyst amount: 0.5 μmol with respect to 1 mol of bisphenol A), the temperature of the fourth polymerization tank was 280 ° C., and butyl p-toluenesulfonate was used with respect to polycarbonate. An aromatic polycarbonate was obtained in the same manner as in Example 1 except that 0 ppm was added. Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0047]

Example 3 In Example 2, the set raw material molar ratio was 1.
035, and the catalyst flow rate was 1.9 mL / hour (set catalyst amount:
An aromatic polycarbonate was obtained in the same manner as in Example 2, except that the amount was set to 0.6 μmol per 1 mol of bisphenol A). Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0048]

Example 4 In Example 1, 1N Na was used as a catalyst.
An OH aqueous solution and a catalyst flow rate of 0.14 L / hour (set catalyst amount: 0.7 μmol per 1 mol of bisphenol A)
Aromatic polycarbonate was obtained in the same manner as in Example 1 except for setting to. Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0049]

Example 5 In Example 2, 1N Na was used as a catalyst.
An OH aqueous solution and a catalyst flow rate of 0.20 L / hour (set catalyst amount: 1.0 μmol per 1 mol of bisphenol A)
Aromatic polycarbonate was obtained in the same manner as in Example 2 except for setting to. Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0050]

Comparative Example 1 In Example 1, the catalyst flow rate was set to 0.96 mL / hour (set catalyst amount:
An aromatic polycarbonate was obtained in the same manner as in Example 1, except that the amount was fixed to 0.3 μmol per 1 mol of bisphenol A). Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0051]

Comparative Example 2 The procedure of Example 2 was repeated except that the catalyst flow rate was fixed at 1.6 mL / hour (set catalyst amount: 0.5 μmol per 1 mol of bisphenol A) without installing a program control device. In the same manner as in 2, an aromatic polycarbonate was obtained. Table 1 shows the evaluation results of the obtained aromatic polycarbonates.

[0052]

[Table 2]

[0053]

According to the production method of the present invention, the amount of the transesterification catalyst to be used can be controlled very accurately, the aromatic polycarbonate produced has a narrow molecular weight distribution, and has an excellent initial hue. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing one example of a production method of the present invention.

[Explanation of symbols]

 1. 1. DPC storage tank Stirring blade 3. BPA hopper 4a, b. Raw material mixing tank 5. 5. DPC flow control valve BPA flow control valve 7,10. Pump 8. 8. Catalyst flow control valve Program control device 11. Catalyst storage tank 12. By-product discharge pipes 13a, b, c. Vertical polymerization tank 14. Max blend wing 15. Horizontal polymerization tank 16. Lattice wing

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Tayama 1-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka F-term in the Kurosaki Office of Mitsubishi Chemical Corporation (reference) 4J029 AA09 AB04 BB10A BB10B BB12A BB13A BB13B BD09A BE04 BF13 BG08X BH02 DB07 DB13 HA01 HC04 HC05A HC05B JA091 JA121 JB131 JB171 JC091 JC231 JC261 JC451 JC731 JC751 JF021 JF031 JF041 JF051 JF121 JF131 JF141 JF151 KA04 KB02 KB05 KE02 LA06 LA09 LA05

Claims (4)

[Claims] 1. An aromatic dihydroxy compound and a carbonic acid diester are used as raw materials, these raw materials are continuously supplied to a raw material mixing tank, and the resulting mixture is continuously supplied to a polymerization tank, and a transesterification catalyst is used. In producing an aromatic polycarbonate by the transesterification method, (1) the set transesterification catalyst amount is set to 1 mol of the aromatic dihydroxy compound or the carbonic acid diester for each of at least one unit production time provided by fractionating the total production time. And (2) at least 95% of the unit production time, when the actual amount of transesterification catalyst supplied is an aromatic dihydroxy compound or carbonic acid. Each set ester exchange catalyst amount ± 0.1 per mole of diester
A method for producing an aromatic polycarbonate, which is maintained at a value within μmol. 2. A method for continuously measuring the supply amount of an aromatic dihydroxy compound or a carbonic acid diester and a catalyst flow rate, and then adjusting the calculated actual transesterification catalyst amount to coincide with the set transesterification catalyst amount. The method for producing an aromatic polycarbonate according to claim 1, wherein the flow rate is automatically controlled. 3. At least 95% of each unit production time
Wherein the actual amount of transesterification catalyst supplied is maintained at a value within ± 0.06 μmol of each set catalyst amount per mol of aromatic dihydroxy compound or carbonic acid diester. For producing aromatic polycarbonate. 4. The method for producing an aromatic polycarbonate according to claim 1, wherein the transesterification catalyst is an alkali metal compound.