JP2002256070A - Method for producing aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for stably producing an aromatic polycarbonate having excellent quality, such as excellent hue, heat resistance and hydrolysis resistance, and having uniform quality. SOLUTION: A diester carbonate and an aromatic dihydroxy compound are used as main raw materials, these raw materials are continuously supplied to a raw material mixing tank, and the obtained mixture is continuously supplied to a polymerization tank, and the aromatic mixture is obtained by an ester exchange method. In producing the polycarbonate, the set raw material molar ratio is set to the carbonate diester compound / aromatic dihydroxy compound = 1.001 to 1.300.
Selected from within the range, operated at one set raw material molar ratio within the range, until the set raw material molar ratio is changed, or until the start of the operation for the end of production, the raw material supplied to the polymerization tank Set the raw material molar ratio ±
A method for producing an aromatic polycarbonate which is maintained at a value within 0.5%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Aromatic polycarbonate resins are widely used as OA parts, automobile parts, building materials, etc. as engineering plastics having excellent mechanical properties such as impact resistance and heat resistance and transparency. Has been
In particular, it is widely used in optical materials such as optical lenses, discs, and optical fibers, and in applications such as sheets, taking advantage of its properties such as impact resistance and transparency. In particular, the appearance of polycarbonate having excellent hydrolysis resistance has been particularly desired.

[0003] As a method for producing an aromatic polycarbonate, a so-called phosgene method in which an aromatic dihydroxy compound such as bisphenol is reacted with phosgene in an interfacial polycondensation method has been industrialized. However, the phosgene method requires the use of phosgene that is harmful to the human body, requires a solvent such as dichloromethane, which has a high environmental load, and the incorporation of large amounts of by-produced sodium chloride into the polymer. Problems such as corrosion when used in electronic components have been pointed out.

On the other hand, a method of transesterifying a carbonic acid diester with an aromatic dihydroxy compound in a molten state to obtain an aromatic polycarbonate while removing low-molecular-weight substances such as phenol by-produced from the system is also known as a so-called melt polymerization method or esterification method. It has long been known as an exchange method, and has the advantage that polycarbonate can be produced without the above-mentioned problems by the interfacial polycondensation method.However, the polymerization rate and the performance of the produced polymer, particularly the hue and thermal stability, Since the terminal hydroxyl group concentration that determines the hydrolyzability and the like is determined by the composition ratio of the raw materials, it is necessary to perform the preparation strictly.

In order to achieve this, for example, Japanese Patent Application Laid-Open
JP-A No. 00-128973 describes that the fluctuation of the raw material composition is kept within a certain value. However, when the batch-type raw material preparation as described in the publication is not performed, for example, a diester carbonate and an aromatic substance are used. When the aromatic dihydroxy compound is continuously supplied to the raw material mixing tank, and the obtained mixture is continuously supplied to the polymerization tank to produce an aromatic polycarbonate by the transesterification method, errors in the instruments and in the raw material mixing tank are required. Therefore, there is a problem that the supply amount of the raw material is not stable due to the pressure fluctuation of the liquid and the blockage of the sublimate or the like in the supply portion of the solid raw material.

On the other hand, Japanese Patent Application Laid-Open No. 2000-178354 discloses that a raw material molar ratio is set for each unit manufacturing time, and at least 95% of each unit manufacturing time is a raw material molar ratio actually supplied to the polymerization tank. Is maintained within a set raw material molar ratio of ± 0.8%, but this is not yet sufficient from the viewpoint of stabilizing the terminal hydroxyl group concentration of the product polymer. Further, this publication proposes a method of analyzing the raw material composition and feeding back the value to the raw material supply in order to finely adjust the fluctuation of the raw material composition ratio based on the instability of the raw material supply, but the system is complicated. Not only become
If an analysis error occurs, there is a problem that the composition ratio of the raw materials is further destabilized.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for stably producing an aromatic polycarbonate having excellent quality, such as excellent hue, heat resistance and hydrolysis resistance, and having uniform quality. To provide.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above circumstances, and as a result, by adopting a specific means, it has been possible to increase the terminal hydroxyl group concentration of the aromatic polycarbonate obtained by the transesterification method. They have found that they can be manufactured stably over time, and have completed the present invention. That is, the gist of the present invention is that transesterification is performed by continuously supplying a diester carbonate and an aromatic dihydroxy compound to a raw material mixing tank, and continuously supplying the obtained mixture to a polymerization tank. When the aromatic polycarbonate is produced by the method, the set raw material molar ratio is adjusted to the carbonate diester compound /
Aromatic dihydroxy compound = Select from the range of 1.001 to 1.300, operate at one set raw material molar ratio within the range, and start operation to change the set raw material molar ratio or to end production In the period up to, the variation of the actual molar ratio of the raw materials supplied to the polymerization tank is set to the set raw material molar ratio ± 0.
A method for producing an aromatic polycarbonate maintained at a value within 5%, which solves the above problem.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically. As a raw material for producing the aromatic polycarbonate according to the present invention, a carbonic acid diester compound and an aromatic dihydroxy compound are used. The carbonic acid diester compound used in the present invention is a compound represented by the following formula (1).

[0010]

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(Wherein, R and R ′ each have 1 to 18 carbon atoms)
Is an aliphatic group or an aromatic group which may be substituted, and R and R ′ may be the same or different. Specific examples of the carbonic acid diester compound represented by the formula (1) include, for example, dimethyl carbonate, diethyl carbonate, di-t-butyl carbonate, diphenyl carbonate and substituted diphenyl carbonate such as ditolyl carbonate. Is preferably diphenyl carbonate, substituted diphenyl carbonate, particularly diphenyl carbonate. These carbonate diester compounds may be used alone or in combination of two or more.

Together with the carbonic acid diester compound as described above, it is preferably at most 50 mol%, more preferably at most 30 mol%.
Dicarboxylic acids or dicarboxylic acid esters may be used in an amount of not more than mol%. Such dicarboxylic acids or dicarboxylic esters include terephthalic acid,
Isophthalic acid, diphenyl terephthalate, diphenyl isophthalate and the like are used. When such a carboxylic acid or carboxylic acid ester is used in combination with a carbonic acid diester compound, a polyester carbonate is obtained.

The aromatic dihydroxy compound used in the present invention is a compound represented by the following formula (2).

[0014]

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(Wherein B is a divalent hydrocarbon group having 1 to 15 carbon atoms, a halogen-substituted divalent hydrocarbon group,
-S- group, -SO ₂ - group, -SO- group, -O- group, or -
X represents a CO- group, and X represents a halogen atom, having 1 to 14 carbon atoms.
Alkyl group, aryl group having 6 to 18 carbon atoms, 1 carbon atom
Oxyalkyl group or oxyaryl group having 6 to 18 carbon atoms. m is 0 or 1, y is 0 to 4
Is an integer. As the aromatic dihydroxy compound represented by the formula (2), for example, 2,2-bis (4-hydroxyphenyl)
Propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-diethylphenyl) propane, 2,2-
Bis (4-hydroxy- (3,5-diphenyl) phenyl) propane, 2,2-bis (4-hydroxy-3,5
-Dibromophenyl) propane, 2,2-bis (4-hydroxyphenyl) pentane, 2,4'-dihydroxy-diphenylmethane, bis (4-hydroxyphenyl)
Methane, bis (4-hydroxy-5-nitrophenyl)
Methane, 1,1-bis (4-hydroxyphenyl) ethane, 3,3-bis (4-hydroxyphenyl) pentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) sulfone,
2,4′-dihydroxydiphenyl sulfone, bis (4
-Hydroxyphenyl) sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-
Examples thereof include 3,3′-dichlorodiphenyl ether and 4,4′-dihydroxy-2,5-diethoxydiphenyl ether. Among these, 2,2-bis (4-hydroxyphenyl) propane (hereinafter, referred to as “bisphenol A”) is preferable. These aromatic dihydroxy compounds can be used alone or in combination of two or more.

The ratio of the carbonic acid diester compound to the aromatic dihydroxy compound to be used is determined by the desired molecular weight of the aromatic polycarbonate and the amount of terminal hydroxy groups. Has a significant effect on the color and hue,
In order to have practical physical properties, it is necessary that the content be 1000 ppm or less. Therefore, it is common to use a carbonate diester compound in an equimolar amount or more with respect to 1 mole of the aromatic dihydroxy compound. 1.300 moles,
Preferably 1.010 to 1.200 mol, especially 1.0
Preferably, it is used in an amount of from 20 to 1.150.

In the melt polymerization reaction between the aromatic dihydroxy compound and the carbonic acid diester compound, a transesterification catalyst is usually used, and in the present invention, an alkali metal compound,
An alkaline earth metal compound is used, and a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound can be used in combination. These catalysts may be used alone or in combination of two or more.

The amount of the catalyst is usually in the range of 1 × 10 ^-8 to 1 × 10 ^-5 mol per mol of the aromatic dihydroxy compound. If less than this amount, the given molecular weight,
The polymerization activity required to produce a polycarbonate having a terminal hydroxy group amount cannot be obtained. If the amount is larger than this amount, the polymer hue is deteriorated and the amount of transparent foreign substances tends to increase. In particular, when an alkali metal compound and / or an alkaline earth metal compound is used, their metal amount is 1 × 1
It is preferably in the range of 0 ^{-8 to} 2 × 10 ^-6 mol, particularly 5 × 10 ^-8 to 1 × 10 ^-6 mol, particularly 2 × 10 ^-7 mol.
A range of 9 × 10 ⁻⁷ mol is preferred.

Specific examples of the alkali metal compound include hydroxides such as lithium, sodium, potassium, rubidium and cesium; inorganic alkalis such as hydrogen carbonate, carbonate, acetate, hydrogen phosphate and phenyl phosphate. Examples thereof include metal compounds, organic acids such as stearic acid and benzoic acid, alcohols such as methanol and ethanol, and organic alkali metal compounds such as salts with phenols such as phenol and bisphenol A. Specific examples of the alkaline earth metal compound, beryllium, calcium, magnesium, strontium, barium hydroxide, hydrogen carbonate, carbonate, acetate and other inorganic alkaline earth metal compounds, organic acids, alcohols, Examples thereof include organic alkaline earth metal compounds such as salts with phenols, among which alkali metal compounds are preferable, and cesium compounds are particularly preferable.

Specific examples of the basic boron compound include tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethylethyl boron, trimethylbenzyl boron, trimethylphenyl boron, triethylmethyl boron, triethylbenzyl boron, triethylphenyl Hydrides such as boron, tributylbenzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, butyltriphenylboron,
Examples thereof include a sodium salt, a potassium salt, a lithium salt, a calcium salt, a magnesium salt, a barium salt, and a strontium salt.

Specific examples of the basic phosphorus compound include, for example, triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and quaternary phosphonium salts. No.
Specific 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, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltriphenylammonium hydroxide, butyltriphenylammonium hydroxide Kishido, and the like.

Specific examples of the amine compound include, for example, 4-aminopyridine, 2-aminopyridine, N, N
-Dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2-dimethylaminoimidazole, 2-methoxyimidazole, imidazole,
2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like can be mentioned.

The molecular weight of the aromatic polycarbonate of the present invention is not particularly limited. However, in order to obtain practical physical properties, the viscosity average molecular weight (Mv) is usually from 14,000 to 50,000, preferably from 15,000 to 30,000. In the production of 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 raw material mixing tank, a raw material buffer tank, a polymerization tank, etc. to which a catalyst is added. And a polymer is produced. In the present invention, in order to keep the raw material molar ratio in the homogeneously stirred mixture of both raw materials supplied to the polymerization tank, first, a target “set raw material molar ratio” is set. This is selected from the range of carbonic acid diester compound / aromatic dihydroxy compound = 1.001 to 1.300 for the reason described above. This set raw material molar ratio does not necessarily have to be a constant value throughout the entire production time, and can be set for each of one or more unit production times provided by dividing the entire production time. In the present invention, the “total production time” or the “unit production time” corresponds to a raw material supply time for stably producing a polymer in a polymerization tank, and is not stable at the time of startup or at the time of grade change. Does not include the raw material supply time.

In the present invention, the actual raw material molar ratio of the raw material mixture supplied to the polymerization tank (hereinafter simply referred to as the “actual raw material molar ratio”) is determined by the time corresponding to the unit production time,
That is, the operation is performed at one set raw material molar ratio, and until the change of the molar ratio, or until the start of the production end operation, the set raw material molar ratio is within ± 0.5%, preferably within ± 0.4%,
Particularly preferably, it is necessary to maintain the value within ± 0.3%, and in order to maintain the value within the set raw material molar ratio ± 0.5%, the measurement accuracy of the raw material supplied to the mixing tank is maintained. The molar ratio of the raw material to be obtained should be higher than the precision. Otherwise, it is difficult to keep the molar ratio of the raw materials constant.

The method of supplying the raw material to the raw material mixing tank is as follows.
Since the liquid state is easier to maintain high measurement accuracy, of the aromatic dihydroxy compound and the carbonic acid diester compound,
Preferably, one or both are melted and supplied in a liquid state, but it is particularly preferable to supply a carbonate diester compound having a relatively low melting point and excellent thermal stability in a liquid state.

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 a measuring device, and a micro motion type flow meter is preferable in terms of accuracy. On the other hand, when the raw material is supplied in a solid state, a capacity type feeder such as a screw type feeder or a weight type feeder such as a belt type or a loss-in-weight type can be used. Is preferable, and a loss-in-weight method is particularly preferable.

As a method of melting the raw material, for example, a method of supplying a raw material in a solid state using the above-described solid feeder to a raw material melting tank maintained at a predetermined temperature condition, or a method such as an extruder There is a method of feeding while melting using an apparatus. When the carbonic acid diester compound can be obtained in a molten state from the carbonic acid diester compound production step, it is preferable to use the carbonic acid diester compound as a raw material to the raw material mixing tank without solidifying it once. When a melting tank is used before mixing the raw materials, the raw material supply accuracy to the melting tank does not necessarily need to be high, but the supply from the melting tank to the mixing tank needs to have high accuracy as described above. Therefore, it is desirable to use a measuring device such as an oval flow meter or a micro motion type flow meter.

Among them, a diester carbonate such as diphenyl carbonate is used at 90 to 150 ° C., preferably 10 to 150 ° C.
In a molten state of 0 to 140 ° C, the mixture is supplied to the raw material mixing tank via a measuring device such as an oval flow meter or a micro motion type flow meter, and aromatic dihydroxy compounds such as bisphenol A, which are inferior in thermal stability, are lost in solid form. It is recommended to use a weight type feeder such as a weight type feeder and supply the raw material to the raw material mixing tank while measuring.

There is also a method of mixing the raw materials in a batch system. However, when the scale is increased, the amount of the raw material prepared at one time increases, so that not only excessive equipment is required but also the amount required for one measurement. Therefore, it is difficult to obtain the accuracy of the weighing device. In order to solve this problem, a method in which a small amount is prepared by dividing into a large number of times is also conceivable.However, since the number of preparations must be increased and a complicated operation needs to be repeated, in the present invention, the raw material is continuously supplied to the raw material mixing tank. A continuous method of supplying and continuously supplying the obtained mixture to a polymerization tank is essential.

The temperature of the raw material mixing tank may be any temperature as long as the raw material is melted. However, if the temperature is too low, it takes a long time to dissolve, and if it is too high, the thermal decomposition of the raw material becomes vigorous. For example, in the case of a reaction between diphenyl carbonate and bisphenol A, the temperature is usually 120 ° C. or higher, preferably 120 to 160 ° C., and particularly preferably 130 to 150 ° C. Further, in order to suppress deterioration of the raw material due to thermal decomposition, oxidation and the like, the inside of the raw material mixing tank is preferably kept under an atmosphere of an inert gas such as nitrogen.

The pressure in the raw material mixing tank is not particularly limited,
In particular, when the solid raw material is fed to the raw material preparation tank, sublimates and volatiles from the raw material preparation tank adhere around the feed port,
In addition to making the supply amount unstable, especially when using a solid feeder by the loss-in-weight method, if the pressure inside the raw material mixing tank is higher than the raw material supply unit to the feeder, the accuracy of the weight detection unit is deteriorated. For this reason, it is preferable that the pressure in the raw material mixing tank is maintained at a negative pressure, and more preferably, the pressure in the raw material mixing tank is -50 to-
10,000 Pa, especially -80 to -5000 Pa, and especially -100 to -500 Pa is suitable.

Further, the pressure fluctuation in the raw material mixing tank causes a fluctuation in the raw material supply amount. In particular, in the case of a solid feeder by the loss-in-weight method, the weight detected by the load cell fluctuates greatly due to the pressure fluctuation, and the flow rate is reduced. There is a problem that the accuracy is not constant and the accuracy is deteriorated. Therefore, the maximum width of the pressure fluctuation is preferably within ± 1000 Pa,
Above all, it is preferably within ± 500 Pa, particularly preferably within ± 300 Pa.

The transesterification is generally carried out continuously in two or more stages, usually in three to seven stages. Specific reaction conditions are as follows: temperature: 150 to 320 ° C., pressure: normal pressure to 1.3 Pa, average residence time: 5 to 150 minutes. In each polymerization tank, phenol which is by-produced as the reaction proceeds. In order to make the discharge of methane more effective, the temperature is set stepwise to a higher temperature and a higher vacuum 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 polymerization reaction is preferably carried out under substantially oxygen-free conditions. For example, before starting the operation, the inside of the raw material adjusting tank, the reactor and the piping are replaced with an inert gas such as nitrogen gas.
A molten mixture of an aromatic dihydroxy compound and a carbonic acid diester compound is supplied to a vertical reactor. The catalyst may be supplied to the raw material mixing tank or the raw material buffer tank, or may be directly supplied to the first reaction tank on a separate line from the raw material. Also,
In a pipe before entering the first reaction tank, the mixture may be supplied in a state of being mixed with the raw material by a static mixer or the like. If necessary, a solvent for dissolving or suspending the catalyst is used. Preferred solvents include water, acetone, phenol and the like.

The polymerization liquid supply port is preferably located at the liquid phase on the side wall of the reaction vessel, and the discharge port is preferably located at the bottom of the reaction vessel. Further, the method of continuously extracting the reaction solution from each tank is performed by a method suitable for the physical properties of the reaction solution, such as a method using a head, a method using a pressure difference, a method using a liquid sending pump such as a gear pump, or the like. Is preferred. The apparatus used in the present invention may be any of a vertical type, a tube type or a tower type, and a horizontal type. Normally, turbine blades, paddle blades, anchor blades, full zone blades (manufactured by Shinko Pantec Co., Ltd.), Sun Meller blades (manufactured by Mitsubishi Heavy Industries, Ltd.), Max Blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), helical ribbons Following one or more vertical polymerization tanks equipped with blades, twisted lattice blades (manufactured by Hitachi, Ltd.), etc., horizontal, single-shaft polymerization tanks such as disk-type and cage-type, HVR, SCR, N-SCR (Mitsubishi) Heavy Industries, Ltd.
Manufactured by Sumitomo Heavy Industries, Ltd., glasses wings, lattice wings (manufactured by Hitachi, Ltd.), or glasses with wing and polymer feeding functions, such as twists and twists It is possible to use a horizontal biaxial type polymerization tank provided with a combination of blades and / or inclined blades.

In the aromatic polycarbonate produced by the method of the present invention, low molecular weight compounds such as a raw material monomer, a catalyst, an aromatic hydroxy compound produced by a transesterification reaction and an aromatic polycarbonate oligomer usually remain. Among them, the carbonic acid diester compound and the aromatic hydroxy compound, which are the raw material monomers, have a large residual amount and adversely affect physical properties such as heat aging resistance and hydrolysis resistance, and are therefore removed when commercialized.

The method for removing them is not particularly limited. For example, devolatilization may be carried out 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.

The extruder used for devolatilization may be single-screw or twin-screw. The twin-screw extruder is a meshing twin-screw extruder, and may rotate in the same direction or in different directions. For the purpose of devolatilization, those having a vent portion after the acidic compound addition portion are preferable. Although the number of vents is not limited, a multistage vent of 2 to 10 stages is usually used. Also,
In the extruder, if necessary, a stabilizer, an ultraviolet absorber,
Additives such as a release agent and a colorant may be added and kneaded with the resin.

[0041]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition,
The obtained aromatic polycarbonate was analyzed 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.

[0042]

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

(3) Raw Material Composition Analysis The raw material collected from the discharge portion of the raw material mixing tank was dissolved in heavy acetone, and a 45 ° pulse and a pulse interval of 30 seconds were measured using NMR (AL-400) manufactured by JEOL Ltd. ¹ H-N under conditions
The MR was measured, and a signal based on the methyl group of bisphenol A (around 1.6 ppm) = A and an aromatic component (6.4)
~ 7.8 ppm) from signal intensity = B to diphenyl carbonate (DPC) and bisphenol A (BP
The molar ratio of A) was determined by the following equation.

[0044]

## EQU2 ## DPC / BPA = (6B-8A) / 10A (4) Hue Using an injection molding machine J100SS-2 (manufactured by Nippon Steel Works Co., Ltd.), conditions of a barrel temperature of 280 ° C. and a mold temperature of 90 ° C. Below, a square sheet having a thickness of 3 mm, a length of 100 mm and a width of 100 mm was injection molded. For this injection molded sheet, use a color tester (SC-
1-CH), the tristimulus value XYZ, which is the absolute value of the color, was measured, and the YI value, which is an index of yellowness, was calculated by the following relational expression. The larger the YI value of is, the more colored it is.

[0045]

## EQU3 ## YI = (100 / Y) × (1.28X-1.06Z) (5) Heat Resistance Test The injection molded sheet obtained in (4) was subjected to a heat treatment at 140 ° C. and 100 ° C.
After the heat treatment for a long time, the YI value was measured.

Example 1 An embodiment of the method for producing an aromatic polycarbonate of the present invention 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 DP
C storage tank, 2 is a stirring blade, 3 is a DPC flow control valve, 4 is a micro motion type flow meter, 5 is a BPA storage tank, and 6 is a BPA
Hopper, 7 is nitrogen seal, 8 is loss-in-weight type B
PA feeder, 9 is a raw material mixing tank, 10 is a vent line, 11 is a raw material buffer tank, 12 is a pump, 13 is a catalyst introduction pipe, 14a, b, c, d are vertical polymerization tanks, 15a,
b, c, d, and e are by-product discharge tubes, 16 is a max blend blade, 17 is a double helical ribbon blade, 18 is a horizontal polymerization tank, and 19 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 205.0 mol / h and a BPA feeder ( 8) to 197.1 mol / h (raw material molar ratio: 1.04
0) weigh with a micro motion type flow meter and a loss-in weight type weight feeder so that
The mixture was continuously supplied to a raw material mixing tank (9) adjusted to 150 ° C. in a nitrogen atmosphere. At this time, the pressure of the BPA hopper (6) was controlled to be 0 Pa (atmospheric pressure), and the pressure of the raw material mixing tank (9) was controlled to be -200 Pa at a gauge pressure where the atmospheric pressure was 0 Pa.

The prepared raw material mixture was supplied through a pump (12) and a raw material introduction pipe to a first vertical column having a capacity of 100 L, which was equipped with a Max blend blade (16) and was controlled at 220 ° C. under normal pressure and nitrogen atmosphere. It is continuously supplied into the mold stirring polymerization tank (14a), and while controlling the valve opening provided in the polymer discharge line at the bottom of the tank so that the average residence time is 60 minutes,
The liquid level was kept constant. Simultaneously with the start of the supply of the above mixture, a 1% by weight aqueous solution of cesium carbonate as a catalyst was 3.2 ml / hour (5 × 10 ⁻⁷ mol per mol of bisphenol A) via a catalyst introduction tube (13). Continuous supply was started at a flow rate of.

The polymerization liquid discharged from the tank bottom is
2nd, 3rd, 4th (2nd, 3rd tank: Max blend blade (16), 4th tank: double helical ribbon blade (17))
And a horizontal polymerization tank (18) having a capacity of 150 L and a fifth lattice blade (19).
Was supplied continuously and continuously. The reaction conditions in the second to fifth 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.

[0050]

Table 1 Temperature Pressure (absolute pressure) Stirring speed 2nd polymerization tank (14b) 220 ° C 13332Pa 110rpm 3rd polymerization tank (14c) 240 ° C 2000Pa 75rpm 4th polymerization tank (14d) 270 ° C 67Pa 75rpm 5th polymerization tank ( 18) During the reaction at 280 ° C. and 67 Pa at 10 rpm, the liquid level was controlled so that the average residence time in the second to fifth polymerization tanks was 60 minutes. Was removed from the by-product discharge pipe (15) equipped with a reflux condenser. The polycarbonate drawn out from the polymer outlet at the bottom of the fifth polymerization tank, in a molten state, was provided with a thermometer for measuring the internal temperature in the kneading section, and a twin-screw extruder equipped with a three-stage vent ( Kobe Steel Ltd., screw diameter 0.046m, L
/ D = 36), 5 ppm of butyl p-toluenesulfonate was added, hydrogenated and devolatilized, and then pelletized. The extruder conditions were as follows: discharge rate = 50 kg / hr, rotation speed =
150 rpm, maximum resin temperature = 278 ° C.

Under the above conditions, the operation was continued for 500 hours. The maximum width of the pressure fluctuation of the raw material mixing tank during the continuous operation was the set value ± 100 Pa. The composition of the raw material collected from the raw material mixing tank discharge section every 6 hours during operation, the Mv of the polymer,
[OH] and YI were analyzed. The results are shown in Table 1. Example 2 Example 2 was carried out in the same manner as in Example 1, except that the set raw material molar ratio was 1.060 and the temperatures of the fourth and fifth polymerization tanks were 260 ° C. The results obtained are shown in Table 1.

Example 3 Example 3 was carried out in the same manner as in Example 1 except that the set raw material molar ratio was changed to 1.030. Table-
1 is shown. Comparative Example 1 Example 1 was carried out in the same manner as in Example 1, except that the pressure of the raw material mixing tank was changed to +10 kPa. Table 1 shows the obtained results. The fluctuation of the raw material composition ratio was large, and the BPA supply line was blocked by the sublimate, and the operation became impossible after 320 hours.

Comparative Example 2 In Example 1, the fluctuation range of the pressure of the raw material mixing tank was 320
Except that it was 0 Pa, it carried out similarly to Example 1. Table 1 shows the obtained results. The fluctuation of the raw material composition ratio was large. Comparative Example 3 In Comparative Example 1, the pressure fluctuation range of the raw material mixing tank was 450
Except that it was 0 Pa, it carried out similarly to the comparative example 1. Table 1 shows the obtained results. The fluctuation of the raw material composition ratio was large, and it became impossible to determine the BPA feeder after 200 hours.

[0054]

[Table 2]

[0055]

According to the method for producing an aromatic polycarbonate of the present invention, the molar ratio of the raw materials in the raw material mixing tank can be controlled stably, and the molecular weight and the amount of terminal OH groups of the aromatic polycarbonate to be produced can vary. And an aromatic polycarbonate excellent in hue, heat resistance and hydrolysis resistance 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. 3. DPC flow control valve Micro motion flow meter 5. BPA storage tank 6. BPA hopper 7. 7. Nitrogen seal 8. Loss-in-weight BPA feeder Raw material mixing tank 10. Vent line 11. Raw material buffer tank 12. Pump 13. Catalyst introduction pipes 14a, b, c, d. Vertical polymerization tank 15a, b, c, d, e. By-product discharge pipe 16. Max blend wing 17. Double helical ribbon wing 18. Horizontal polymerization tank 19. Lattice wing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junji Takano 1-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside the Kurosaki Office of Mitsubishi Chemical Corporation (72) Inventor Tadashi Yamamoto 1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture No. 1 F-term in Kurosaki Office of Mitsubishi Chemical Corporation (reference) 4J029 AA09 AB05 AC01 BB10A BB10B BB12A BB12B BB13A BB13B BE05A BE05B BF14A BF14B BG07X BG08X BH02 DB07 DB11 DB13 HC04A HC05A J091JJJJJJJJJJJJJJJJJJJ1J1J01C JF041 JF051 JF121 JF131 JF141 JF151 JF161 KB02 KD07 KE02 KE05 KE07 KE15 LA01 LA05 LA08 LA14

Claims (5)

[Claims] 1. A diester carbonate and an aromatic dihydroxy compound are used as main raw materials. These raw materials are continuously supplied to a raw material mixing tank, and the obtained mixture is continuously supplied to a polymerization tank to carry out aromatic exchange by a transesterification method. In producing the aromatic polycarbonate, the set raw material molar ratio is set to the carbonic acid diester compound / aromatic dihydroxy compound = 1.001 to 1.300.
Selected from within the range, operated at one set raw material molar ratio within the range, until the set raw material molar ratio is changed, or until the start of the operation for the end of production, the raw material supplied to the polymerization tank Set the raw material molar ratio ±
A method for producing an aromatic polycarbonate, which is maintained at a value within 0.5%. 2. The method for producing an aromatic polycarbonate according to claim 1, wherein the pressure in the raw material mixing tank is maintained at a negative pressure. 3. The method for producing an aromatic polycarbonate according to claim 1, wherein the pressure in the raw material mixing tank is −50 Pa to −10000 Pa at a gauge pressure where the atmospheric pressure is 0 Pa. 4. The method according to claim 1, wherein the maximum width of the pressure fluctuation in the raw material mixing tank is within a set value ± 1000 Pa.
The method for producing an aromatic polycarbonate according to any one of claims 1 to 3. 5. The method for producing an aromatic polycarbonate according to claim 1, wherein at least one of the raw materials supplied to the raw material mixing tank is a solid.