JP2000212270A - Production of aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for stably producing aromatic polycarbonates excellent in hue and reduced in the variation of molecular weight, which solves the problem of the quality of polycarbonates to be obtained by a transesterification method. SOLUTION: In the process for producing an aromatic polycarbonate by subjecting an aromatic dihydroxy compound and a carbonate diester to continuous melt polycondensation in the presence of a transesterification catalyst, at least the part of an addition device 22 and a device annexed thereto to be placed in the reaction tank which comes into contact with a catalyst solution is constituted of a material having a contact angle to the catalyst solution of not smaller than 50 deg. in transporting the catalyst solution dissolving a transesterification catalyst in a solvent from a catalyst solution tank 2 to a reaction tank 4a to be added to a melt therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing an aromatic polycarbonate having excellent hue and having no fluctuation in the molecular weight in the continuous polycondensation of an aromatic dihydroxy compound and a carbonic acid diester in the presence of a transesterification catalyst. About the method.

[0002]

2. Description of the Related Art Aromatic polycarbonates have high impact resistance,
It is a resin excellent in various physical properties such as dimensional stability and transparency, and is used in a wide range of fields. Examples of its industrial production method include a phosgene method (interfacial polymerization method) and a transesterification method (melt polymerization method). In the latter transesterification method, the process is relatively simple compared to the phosgene method, and not only can it exhibit advantages in terms of operation and cost, but it does not use highly toxic phosgene or halogen-based compounds such as methylene chloride. Has recently been reviewed. However, in the conventional method for producing a polycarbonate by a transesterification method, an aromatic dihydroxy compound and a carbonic acid diester are heated and melted, and polycondensed under high temperature and high vacuum conditions in the presence of a catalyst to produce a colored product. There was an easy problem.

Various studies have been made to solve this problem. For example, JP-A-5-125168 discloses a method of using a material having a nickel and / or aluminum content of 60% or more as a material of a reactor, and JP-A-5-125172 discloses a method of using nickel and / or chromium. There has been proposed a method of using a material having a content of 60% or more, but these materials are expensive, and thus have a problem of poor practicality.

In order to modify the surface of a reactor, Japanese Patent Application Laid-Open No. 4-332725 discloses a method in which a material in which a liquid contact portion of a reactor is plated with chromium or nickel is used. Japanese Patent Application Laid-Open No. 6-56984 discloses a method of reducing the surface roughness Rmax of at least a part of the inner wall surface of a stainless steel pipe through which a molten polymer passes to 5 μm or less. A method of washing a stainless steel reactor with a liquid containing a compound has been proposed.However, even in these methods, metal elution is unavoidable, and a polycarbonate having a satisfactory hue is stably produced. Was not enough.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for producing a transesterified aromatic polycarbonate stably, which is excellent in hue and has no fluctuation in molecular weight.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, a material having a contact angle with the catalyst solution of a specific value or more has been removed from the contact portion with the catalyst solution. It has been found that an aromatic polycarbonate having an excellent hue can be stably produced by using the material of the invention, and the present invention has been completed.

That is, the present invention provides a method for producing an aromatic polycarbonate by continuously melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester in the presence of a transesterification catalyst, wherein the transesterification catalyst is dissolved in a solvent. When the catalyst solution thus prepared is transferred from the catalyst solution tank to the reaction tank and added to the melt in the tank, at least the catalyst solution of an addition device installed in the reaction tank and a device attached thereto is brought into contact with the catalyst solution. The portion relates to a method for producing an aromatic polycarbonate, wherein the portion is made of a material having a contact angle with a catalyst solution of 50 ° or more.

[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 dihydroxy compound and a carbonic acid diester are used as raw materials, and are continuously melt-polycondensed in the presence of a transesterification catalyst to produce an aromatic polycarbonate.

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]

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(Wherein A is a single bond, an optionally substituted linear, branched or cyclic 2-10 carbon atom)
A divalent hydrocarbon group or a divalent group represented by —O—, —S—, —CO— or —SO ₂ —, and X and Y
Is a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and p and q are each 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-methyl) Phenyl) 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)
Bisphenols such as propane, 4,4-bis (4-hydroxyphenyl) heptane and 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′- Tetramethyl-
Biphenols such as 4,4'-dihydroxybiphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone and the like 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 (also referred to as "bisphenol A" and sometimes abbreviated as BPA) is preferred.

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

[0014]

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(In the formula, A ′ is a linear, branched or cyclic, monovalent hydrocarbon group having 1 to 10 carbon atoms which may be substituted. May be different.)

Typical examples of the carbonic acid diester include diphenyl carbonate; substituted diphenyl carbonate represented by ditolyl carbonate; dimethyl carbonate, diethyl carbonate, di-t-butyl carbonate and the like. These carbonic diesters
They can be used alone or in combination of two or more.
Of these, diphenyl carbonate (sometimes abbreviated as DPC) and substituted diphenyl carbonate are preferred.

The above-mentioned carbonic acid diester may be substituted with a dicarboxylic acid or a dicarboxylic acid ester in an amount of preferably 50 mol% or less, more preferably 30 mol% or less. Representative dicarboxylic acids or dicarboxylic esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate, and the like. When substituted with such a dicarboxylic acid or dicarboxylic acid ester, a polyester carbonate is obtained.

These carbonic acid diesters (including the above substituted dicarboxylic acids or esters of dicarboxylic acids; the same applies hereinafter) are used in excess with respect to the aromatic dihydroxy compound. That is, 1.001 to 1.300, preferably 1.010 to aromatic dihydroxy compound.
Used at a molar ratio of 1.200. Under the same reaction conditions, as the molar ratio decreases in this range, the reaction rate increases, and the viscosity average molecular weight of the polycarbonate increases. In addition, when the molar ratio is increased in this range, the reaction rate decreases, and the viscosity average molecular weight decreases. The molar ratio is 1.
When it is smaller than 001, the amount of terminal OH groups of the obtained polycarbonate increases, and the reactivity increases,
Thermal stability, hydrolysis resistance, etc. are lowered, and are not suitable for ordinary use. If it exceeds 1.300, it will be difficult to produce an aromatic polycarbonate having a desired molecular weight.

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 compound such as a basic phosphorus compound, a basic ammonium compound or an amine compound is used. They are,
One type may be used, or two or more types may be used in combination. The amount of the catalyst to be used is usually 1 × 10 ⁻⁹ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol, per 1 mol of the aromatic dihydroxy compound.

As the alkali metal compound, lithium,
There are inorganic alkali metal compounds such as sodium, potassium, rubidium and cesium hydroxides, carbonates and bicarbonates, and organic alkali metal compounds such as alcohols, phenols and salts with organic carboxylic acids. 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, magnesium, calcium, strontium and barium 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 tetramethyl boron, tetraethyl boron, tetrapropyl boron, tetrabutyl boron, trimethyl ethyl boron, trimethyl benzyl boron, trimethyl phenyl boron, triethyl methyl boron, triethyl benzyl boron, triethyl phenyl boron. , Tributyl benzyl boron, tributyl phenyl boron, tetraphenyl boron, benzyl triphenyl boron, methyl triphenyl boron, butyl triphenyl boron, etc., sodium salt, potassium salt, lithium salt, calcium salt, magnesium salt, barium salt, or strontium There are salts and the like.

As the basic phosphorus compound, for example, trivalent phosphorus compounds such as triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, tributylphosphine, and the like; There are quaternary phosphonium salts derived from compounds.

Examples of the basic ammonium compound include 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 There methyltriphenylphosphonium ammonium hydroxide, butyl triphenyl ammonium hydroxide and the like.

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, alkali metal compounds are practically desirable.

In the method of the present invention, the above-mentioned transesterification catalyst is used in the form of a catalyst solution dissolved in a solvent such as water, acetone, alcohol, toluene, phenol, the above-mentioned raw material aromatic dihydroxy compound or carbonic acid diester. In these solvents, water is preferred, and when an alkali metal compound is used as a catalyst, the catalyst solution is preferably an aqueous solution.

The catalyst solution is supplied to the reaction tank via a catalyst solution tank for preparing or storing the catalyst solution, a transfer pipe for transferring the catalyst solution from the catalyst solution tank to the reaction tank, and an addition device installed in the reaction tank. Added to the melt inside. here,
The reaction tank is a tank in which a melt of an aromatic dihydroxy compound and / or a carbonic acid diester as a raw material is stored or circulated, and a raw material mixing tank, a raw material storage tank, and a polymerization capable of removing by-products. Including tanks.

In the present invention, it is necessary that at least a portion of the above-mentioned addition device and the device attached thereto that comes into contact with the catalyst solution is made of a material having a contact angle with the catalyst solution of 50 ° or more. is there. The simplest addition device may be a straight pipe with the transfer pipe extended into the reaction tank,
An annular or rod-shaped hollow body having a plurality of ejection ports may be connected to the end of the extended straight pipe. If the contact angle with the catalyst solution is less than 50 °, the catalyst solution becomes too wet with the material in contact with the material, so that the material components dissolve into the solution and cause coloring, and the dropping speed is low. When the polycarbonate becomes stable, the molecular weight of the obtained polycarbonate fluctuates, and stable production cannot be performed, which is not preferable.

Examples of the material having a contact angle of 50 ° or more with the catalyst solution include polymers such as fluororesin and silicone resin. In addition, a metal layer formed by a chemical vapor deposition method, a physical vapor deposition method, a spray method, a lining, or the like and having a surface layer of these polymers can be used.
In addition, metals, glasses, ceramics and the like can be used as they are as long as the contact angle with the catalyst solution is 50 ° or more, or by performing a surface treatment such as controlling the surface roughness to reduce the contact angle. It can be used at an angle of 50 ° or more. As an example of the surface treatment, for example, an electrolytic polishing treatment of a stainless steel surface can be mentioned. SU as stainless steel
S304, SUS304L, SUS309S, SUS3
10S, SUS316, SUS316L, and the like. In particular, it is preferable to use a material having a contact angle of 80 ° or more in at least a portion of the addition device and the device attached to the reaction tank that come into contact with the catalyst solution.

Further, the addition device and the device attached to the addition device which are installed in the reaction tank are parts which are in direct or indirect contact with the reaction tank, and are preferably those which do not melt or decompose due to the heat of the reaction tank. It is preferable to use those having a continuous use temperature of 140 ° or more as determined by the Electrical Appliance and Material Control Law. If the continuous use temperature is less than 140 °, it may dissolve in the polymerization system during operation, or the operation may become unstable,
It tends to cause polycarbonate to be colored. As the addition device and the device attached thereto in the reaction tank, in particular, a surface layer is formed with the resin on the inner wall of a tube made of a fluorine resin, a silicon resin or the like, or a metal pipe made of a stainless steel or the like.

Next, a method for producing an aromatic polycarbonate according to the present invention will be described. In the present invention, any apparatus can be used as the polymerization apparatus. Usually, turbine blades, paddle blades,
Anchor wing, full zone wing (Shinko Pantech Co., Ltd.)
1) equipped with a Sun-Meller wing (Mitsubishi Heavy Industries, Ltd.), a Max Blend wing (Sumitomo Heavy Industries, Ltd.), a helical ribbon wing, a twisted lattice wing (Hitachi, Ltd.) Following two or more vertical polymerization tanks, horizontal and single-shaft polymerization tanks such as a disk type and a cage type, HVR, SCR,
N-SCR (manufactured by Mitsubishi Heavy Industries, Ltd.), Vivolac (manufactured by Sumitomo Heavy Industries, Ltd.), or a horizontal twin-screw polymerization tank equipped with spectacle wings, lattice wings (manufactured by Hitachi, Ltd.), etc. , Can be used in combination.

Next, FIG. 1 shows an example of an apparatus used in the continuous polymerization method of the present invention. As an aromatic dihydroxy compound,
An example in which bisphenol A is used as a carbonic acid diester and diphenyl carbonate is used as a raw material will be described.

In FIG. 1, five polymerization tanks are installed in series. In the figure, 1 is a raw material introduction pipe, 2 is a catalyst solution tank, 21 is a transfer pipe, 22 is an addition device, 3 is a by-product discharge pipe, 4a,
Reference numerals 4b, 4c, and 4d denote vertical polymerization tanks, 5 denotes a max blend stirring blade, and 6 denotes a double helical ribbon blade. Also, 7
Denotes a horizontal polymerization tank, 8 denotes a lattice blade, and 9 denotes a final product polymer.

First, a molten mixture of bisphenol A and diphenyl carbonate is introduced into the first polymerization tank (4a) through a raw material introduction pipe (1) under an atmosphere of an inert gas such as nitrogen gas. A catalyst solution obtained by dissolving an alkali metal compound, an alkaline earth metal compound, a basic compound and the like in a solvent is transferred from the catalyst solution tank (2) to the polymerization tank via a transfer pipe (21) and an addition device (22). (4a), and continuously fed into each polymerization tank (4a).
In (4b), (4c), and (4d), while removing by-product phenol from the by-product discharge pipe (3), the melt weight is determined using each of three to seven stages of polymerization tanks (five in FIG. 1). Perform condensation.

The reaction conditions are as follows: temperature: 150 to 320
° C, pressure: normal pressure to 0.01 Torr, average residence time: 5
To 150 minutes, and each polymerization tank (4a) (4b) (4
c) In (4d), in order to make the emission of phenol by-produced as the reaction proceeds (3) more effective, a higher temperature and a higher vacuum are set stepwise within the above reaction conditions. . In order to prevent deterioration of the hue and the like of the obtained polycarbonate, it is preferable to set the temperature as low as possible and the residence time as low as possible.

In the aromatic polycarbonate produced by the above method, both raw materials, a catalyst, a low molecular weight compound such as a hydroxy compound and a polycarbonate oligomer by-produced in the transesterification reaction remain. Above all, both raw materials and the hydroxy compound have a large residual amount and adversely affect physical properties such as heat aging resistance and hydrolysis resistance.

Therefore, as a method for removing them,
It may be devolatilized continuously by a vented extruder. At that time, the basic transesterification catalyst remaining in the resin,
By previously neutralizing and deactivating with an acidic compound or a derivative thereof, a side reaction during devolatilization can be suppressed, and the remaining raw materials and the hydroxy compound can be efficiently removed.

The acidic compound or derivative thereof 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. Among these acidic compounds and derivatives thereof, sulfonic acids and esters thereof are particularly preferable.

The solvent for dissolving the acidic compound or its derivative may be any solvent as long as the above-mentioned acidic compound or its derivative is dissolved, and water is particularly preferable. For acidic compounds or derivatives thereof insoluble in water alone, it is also preferable to use a mixed solvent obtained by adding an organic solvent such as acetone to water. When an organic solvent is used, acetone, aliphatic, or aromatic hydrocarbon compounds that do not adversely affect the polycarbonate are particularly preferably used. However, alcohols and halogen-containing solvents are preferably avoided because they cause depolymerization and coloring of the obtained polycarbonate resin. The amount of the acidic compound or a derivative thereof used is 0.1 to 50 times, preferably 0.5 to 50 times, the molar amount of the basic transesterification catalyst used in the polycondensation reaction.
It is added in a 30-fold molar range.

The extruder used may be of any type as long as it has a vent. Specifically, a vent-type single-screw or multi-screw extruder may be mentioned, but a meshing twin-screw extruder is particularly preferable, and the rotation direction may be the same direction rotation or different direction rotation. Although the number of vents is not limited, a multistage vent having 2 to 10 stages is usually used. In the case of an extruder provided with a multistage vent port, the addition of an acidic compound or a derivative thereof is added before the vent port closest to the resin supply port. As a form of the resin to be subjected to the neutralization and devolatilization treatment by the extruder, a method in which the resin is introduced into an extruder while being in a molten state immediately after polymerization is preferably processed, but once cooled and solidified, introduced into the extruder and processed. It may be a method. The extruder can also add additives such as a stabilizer, an ultraviolet absorber, a release agent, and a coloring agent, if necessary, and knead the resin with the resin.

[0042]

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) The intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured using an Ubbelohde viscometer, and the viscosity average molecular weight (Mv) was determined from the following equation. [Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83

(2) Hue A 10% methylene chloride solution was applied to a 25 mm diameter and 55 m height.
m, and the tristimulus value XYZ, which is the absolute value of the color, was measured with a color tester (Color Tester SC-1 manufactured by Suga Test Instruments Co., Ltd.). Certain YI values were calculated. YI = (100 / Y) × (1.28X−1.06Z) The larger the YI value, the more colored.

(3) Contact Angle A catalyst solution was dropped on the surface of the material degreased with acetone using a contact angle meter (liquid method: manufactured by Kyowa Kagaku Co., Ltd.), and the radius r and height h of the droplet were measured. The contact angle θ was calculated. θ = 2 × tan ⁻¹ (h / r)

(4) Continuous Use Temperature A ministerial ordinance that stipulates technical standards for electrical appliances (total ministerial ordinance No. 46)
No.-1987), the "operating temperature upper limit" was estimated from the temperature at which the tensile breaking strength (JIS K7113) decreased to 50% in 40,000 hours, and the temperature was used as the continuous operating temperature.

Example 1 In a nitrogen gas atmosphere, a mixed mixture of bisphenol A and diphenyl carbonate at a fixed molar ratio (DPC / BPA molar ratio = 1.040) was adjusted to a total of 88.7 kg / hour. At the flow rate, through the raw material introduction pipe, equipped with Max blend blades, normal pressure,
A first 100 L capacity controlled at 210 ° C. in a nitrogen atmosphere
The liquid was continuously supplied into a vertical stirring polymerization tank, and the liquid level was kept constant while controlling the opening of a valve provided in a polymer discharge line at the bottom of the tank so that the average residence time was 30 minutes. Simultaneously with the start of the supply of the above mixture, an aqueous cesium carbonate solution having a concentration of 3.2 × 10 ⁻² wt% as a catalyst was added.
200 ml / hour (1 x 1 mol of bisphenol A)
(10 ⁻⁶ mol). At this time, the catalyst solution prepared in advance is stored in a fluororesin-coated SUS304 catalyst solution tank and passed through a fluororesin tube (θ = 110 °, continuous use temperature = 250 ° C) as a transfer pipe and an addition device. It was continuously fed to the reactor.

The polymerization liquid discharged from the tank bottom is
With stirrers of the second, third and fourth (second and third tanks: Max blend blades, fourth tank: double helical ribbon blades)
The polycarbonate which was sequentially and continuously supplied to a vertical polymerization tank having a capacity of 100 L and a horizontal polymerization tank having a capacity of 150 L provided with a fifth lattice blade, and extracted from a polymer outlet at the bottom of the fifth polymerization tank, was passed through a vented extruder. It was devolatilized, cooled and pelletized.

When the polymerization liquid was introduced into the third, fourth and fifth polymerization tanks, the following set temperatures, pressures and stirring speeds were previously adjusted. Second polymerization tank (210 ° C., 100 Torr, 110 rp)
m) Third polymerization tank (240 ° C, 15 Torr, 75 rp)
m) 4th polymerization tank (270 ° C, 0.5 Torr, 75 rp)
m) Fifth polymerization tank (280 ° C, 0.5 Torr, 10 rp)
m) That is, with the progress of the reaction, the conditions were set to high temperature, high vacuum, and low stirring speed, and the target of the viscosity average molecular weight of the obtained polycarbonate was set to 22000 to 23000. During the reaction, the liquid level was controlled so that the average residence time in the second to fifth polymerization tanks was 60 minutes, and at the same time, phenol by-produced was distilled off.

Sampling was performed 10 to 2 minutes after the start of polymerization.
Performed after 0 and 30 hours. The viscosity average molecular weight (Mv) of the obtained polycarbonate was 22,200, 22,500,
22100, and the hue YI is 1.4, 1.5, 1.4.
Met.

Example 2 In Example 1, a silicone resin tube (θ = 90) was used instead of the fluororesin tube.
°, continuous use temperature = 240 ° C), except that polycarbonate was produced in the same manner as in Example 1. The viscosity average molecular weight (M
v) is 22,500, 22800, 22800;
Hue YI was 1.6, 1.7, 1.8.

[Example 3] In Example 1, an SUS304 tube (θ =
Polycarbonate was produced under the same reaction conditions as in Example 1 except that 62 °) was used. The viscosity average molecular weight (Mv) of the finally obtained polycarbonate is 2180
0, 22800, and 22200, and the hue YI is 1.
9, 2.2 and 2.1.

Comparative Example 1 A polycarbonate was produced in the same manner as in Example 1, except that a SUS304 tube (θ = 34 °) was used as the addition device. The molecular weight was not stable, and the viscosity average molecular weight (Mv) of the obtained polycarbonate was 19900, 1920
0, 21100, the hue YI obtained was 2.2, 2.8,
2.4.

Table 1 shows the results of the above Examples and Comparative Examples.
It was shown to.

[0055]

[Table 1]

[0056]

According to the method of the present invention, an aromatic polycarbonate having an excellent hue and having no fluctuation in molecular weight can be stably obtained in the production of a transesterification method between an aromatic dihydroxy compound and a carbonic acid diester by continuous polycondensation. .

[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. Raw material introduction pipe 2. Catalyst solution tank 21. Transfer piping 22. Addition device 3. By-product discharge pipes 4a, 4b, 4c, 4d. Vertical polymerization tank 5. Max blend stirring blade 6. 6. Double helical ribbon wing 7. Horizontal polymerization tank Lattice wing 9. End product polymer

Continued on the front page (72) Inventor Michio Kawai 1 Tohocho, Yokkaichi-shi, Mie Mitsubishi Chemical Corporation Yokkaichi Office (72) Inventor Katsushige Hayashi 2-4-1 Hinagahigashi, Yokkaichi, Mie Prefecture Inside the Yokkaichi Plant of Chemical Co., Ltd. BD09A BE05A BF14A BG08X BH02 DB13 HC04A HC05A LA01 LB01

Claims (4)

[Claims] 1. A method for producing an aromatic polycarbonate by continuously melt-polycondensing an aromatic dihydroxy compound and a diester carbonate in the presence of a transesterification catalyst, wherein a catalyst solution comprising a transesterification catalyst dissolved in a solvent. Is transferred from the catalyst solution tank to the reaction tank, when adding to the melt in the tank, at least a portion of the addition device installed in the reaction tank and the device attached thereto, which is in contact with the catalyst solution, A method for producing an aromatic polycarbonate, comprising a material having a contact angle with a catalyst solution of 50 ° or more. 2. The method according to claim 1, wherein the adding device and the device attached thereto are:
At least the part in contact with the catalyst solution has a continuous use temperature of 1
The method for producing an aromatic polycarbonate according to claim 1, wherein the method is constituted by a material having a temperature of 40 ° C or higher. 3. The method of claim 1, wherein the adding device and the device attached thereto are:
The method for producing an aromatic polycarbonate according to claim 1, wherein at least a portion in contact with the catalyst solution is made of a material having a contact angle with the catalyst solution of 80 ° or more. 4. The method according to claim 1, wherein the catalyst solution is an aqueous solution.