JPH10218985A - Production of aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a high-mol.-wt. arom. polycarbonate excellent in color at a low cost in a short time. SOLUTION: A prepolymer of an arom. polycarbonate is further polymerized in a horizontal single-shaft polymerizer 17. The polymerizer 17 is equipped with a rotating shaft 10, circular boards 11, 11' installed almost vertically to the shaft 10, and flat blades 12 installed between the circular boards. Each of the blades 12 has one end bent into an L-shape and is installed so that it forms an acute angle with the tangential line of the periphery of the circular boards at the side of the direction of the rotation and so that the bent part of the blade 12 faces from the rear position to the shaft core in relation with the rotation direction. Moreover, hollow circular partition boards 13 are installed almost vertically to the blades 12 and are arranged with the installation distances and inner diameters increased gradually toward the down stream side of the treated liq. The widths of the blades 12 are gradually decreased toward the downstream side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an aromatic polycarbonate by a transesterification reaction. More specifically, the present invention relates to a method for producing an aromatic polycarbonate having an improved hue at low cost in a short time from an aromatic diol 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. Therefore, in recent years, a method for producing a polycarbonate by using a diester carbonate such as diphenyl carbonate and an aromatic diol compound such as bisphenol A as a reaction raw material in a molten state without solvent in the melt without using these compounds has recently been proposed. It has been proposed and partially put into practical use.

In the reaction between diphenyl carbonate and bisphenol A, the viscosity of the reaction mixture increases with an increase in the molecular weight of the polymer to be produced. Therefore, this reaction usually needs to be carried out using a multi-stage polymerization tank. (See JP-A-2-153925, JP-A-6-157939, etc.). In particular, in the late stage of the polymerization step, the viscosity becomes very high (10,000 poise or more), and thus it is difficult to efficiently remove by-products such as phenol from the reaction mixture. For this reason, various methods for performing polymerization using a high-viscosity horizontal polymerization apparatus having a special stirring method have been proposed.

For example, JP-A-4-106126 and JP-A-4-142329 disclose a method of producing an aromatic polycarbonate by melt-polycondensing an aromatic diol compound and diphenyl carbonate by a transesterification method. After performing the polycondensation reaction in a tank reactor,
A production method for obtaining an aromatic polycarbonate having a viscosity average molecular weight of 10,000 to 30,000 using at least one vent extruder, and a paddle type self-cleaning twin screw extruder for obtaining a viscosity average molecular weight of 12, 000
Production methods for obtaining ~ 60,000 aromatic polycarbonates are disclosed respectively.

Japanese Patent Application Laid-Open No. 63-23926 discloses a method for producing polycarbonate using a twin-screw vent-type kneading extruder having blades combining a screw and a paddle. Discloses a method for producing polycarbonate using a horizontal biaxial polymerization apparatus equipped with a so-called lattice blade, and further discloses a method disclosed in
Japanese Patent No. 27265 discloses a method for producing polycarbonate using a vivolac (manufactured by Sumitomo Heavy Industries, Ltd.).

[0006] All of these horizontal apparatuses are very expensive apparatuses of the biaxial type, but promote the increase in the molecular weight of the polymer (mechanical improvement of the surface renewal frequency of the polymer to increase the efficiency of by-product removal). It was an indispensable device to achieve this. This is because, when the polymer viscosity becomes very high, in a horizontal single-shaft apparatus having a disk blade having a central axis usually used in polymerization of polyethylene terephthalate or the like, the reaction polymerization liquid stays near the central axis and the disk blade may be removed. It was difficult to efficiently remove by-products from the reaction polymerization solution, and it was considered that achieving a high molecular weight polycarbonate by the transesterification method was extremely difficult. .

[0007] However, in the polymerization using the above-mentioned horizontal twin-screw device, although the degree varies depending on the structure of the blade, the local heating effect due to the shearing force between the agitated blade and the blade is unavoidable, and the polymerization is easily performed. Although high molecular weight can be achieved, there is a problem that quality such as hue is deteriorated. Also,
In the scale-up of these horizontal biaxial devices, the ratio of the free surface per unit volume decreases, so the efficiency of removing by-products from the reaction mixture also decreases,
In general, the residence time had to be increased, and there was also a situation in which the necessity of a large-sized device having a scale-up ratio or more or an increase in the number of devices had to be taken and the economy was not excellent.

[0008] Recently, a horizontal single-shaft having a rotating body having a structure in which hollow discs having a central axis removed as shown in JP-A-8-283417 and JP-A-8-337648 are connected by inclined blades is disclosed. An example of application to the production of aromatic polycarbonate by the transesterification method of a polymerization apparatus is also disclosed.However, when this apparatus is applied to continuous polymerization, the viscosity of the treatment liquid increases greatly from the apparatus inlet to the outlet. For example, in a region where the processing liquid has a low viscosity, the thin film is not sufficiently and stably formed by the scraping of the processing liquid by the inclined blades and subsequent free fall. Due to the phenomenon that the processing solution stays in the space formed by the hollow disk and the inclined blades, the polymerization speed decreases, the quality such as hue decreases, or stable operation cannot be continued. There has been a Rutoitta problems.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for producing a high molecular weight aromatic polycarbonate excellent in hue at a low cost in a short time. It is in.

[0010]

In view of the above situation, the present inventors have conducted various studies on the production of polycarbonate by a transesterification method using a horizontal uniaxial polymerization apparatus. As a result, one end of the apparatus was placed along the inner wall of the apparatus in the axial direction. By finely adjusting and setting the structure of a horizontal rotating body composed of a plurality of inclined plate blades arranged from the other end to the other end and a plurality of hollow disks attached substantially perpendicular to the inclined plate blades, It has been found that a high-molecular-weight polymer excellent in the above can be stably obtained in a short time, and the present invention has been completed.

That is, the present invention provides a method for producing an aromatic polycarbonate by subjecting an aromatic diol compound and a carbonic acid diester to a transesterification reaction. 2,000 to 18,000 prepolymers are produced, and the prepolymers are treated in a horizontal polymerization apparatus having a processing solution inlet, an outlet and a volatile matter outlet,
A rotary shaft inserted coaxially with the axis of the polymerization device from the outside at both ends in the longitudinal direction of the polymerization device, and disks attached substantially perpendicular to the rotation shaft, one end of which is L A plurality of flat blades slightly bent so as to form a letter shape are formed such that the flat blades have an inclination angle of α (0 ° <α <90 °) with respect to the rotation direction side of the outer peripheral tangent of the disk. In addition, the plate blade is provided such that a bent portion at one end thereof is directed toward the axis from a position rearward with respect to the rotation direction, and that a slight gap is provided with the inner wall surface of the polymerization apparatus. On the other hand, a hollow partition disk is arranged so as to be substantially perpendicular to the processing liquid from the inlet to the outlet so as to gradually increase the interval and inner diameter from the inlet to the outlet, and the blade width of the flat blade is reduced stepwise. Hollow circuit having a structured structure Guided in lateral uniaxial polymerization apparatus equipped with a body, there is provided a further process for producing an aromatic polycarbonate, characterized in that for the polycondensation reaction of the prepolymer.

In the present invention, the rotation speed of the hollow rotator in the horizontal uniaxial polymerization apparatus is set to 2 to 15 rpm, and the temperature is set to 240 to 3 rpm.
An object of the present invention is to provide a method for producing the above-mentioned aromatic polycarbonate, wherein the polycondensation reaction is carried out at a temperature of 50 ° C., a pressure of 3 torr (Torr) or less, and a residence time of 10 to 120 minutes.

Further, the present invention provides a polymer having a higher molecular weight than the prepolymer and having a viscosity average molecular weight of 10,000 to 40,40.
2,000 aromatic polycarbonates are provided.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing an aromatic polycarbonate according to the present invention will be specifically described. In the present invention, an aromatic diol compound and a carbonic acid diester are used as raw materials for producing an aromatic polycarbonate. Aromatic diol compound: The aromatic diol compound used in the production of the present invention can be a compound represented by the general formula (1).

[0015]

Embedded image

(Wherein A is a single bond, a substituted or unsubstituted linear, branched or cyclic divalent hydrocarbon group having 1 to 10 carbon atoms, -O-, -S-, -CO -, -SO _2- , selected from the group consisting of divalent groups represented by
And Y are the same or different and are selected from halogen or a hydrocarbon group having 1 to 6 carbon atoms, and p and q are integers of 0 to 2. )

Some representative examples include, for example, bis (4-hydroxyphenyl) 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, bisphenols such as 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4′-dihydroxybiphenyl,
Biphenols such as 3 ', 5,5'-tetramethyl-4,4'-dihydroxy-biphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, And bis (4-hydroxyphenyl) ketone. Among these, 2,2-bis (4-hydroxyphenyl) propane is preferred.

Two or more of these compounds can be used in combination (copolymer). When a branched aromatic polycarbonate is to be produced, a small amount of a trihydric or higher polyhydric phenol is copolymerized. You can also.

Diester carbonate: Diester carbonate includes dimethyl carbonate, diphenyl carbonate,
Ditolyl carbonate, bis (4-chlorophenyl) carbonate, bis (2,4,6-trichlorophenyl)
There are carbonates and the like.

Transesterification catalyst : In the melt polycondensation reaction between an aromatic diol compound and a carbonic acid diester, a transesterification catalyst is usually used. As the transesterification catalyst, an alkali metal compound, an alkaline earth metal compound, a quaternary ammonium salt, and a phosphonium salt are preferably used. As such an alkali metal compound and an alkaline earth metal compound, specifically, an organic acid salt, an inorganic acid salt, an oxide, a hydroxide, a hydride or an alcoholate of an alkali metal or an alkaline earth metal is preferably used. No.

More specifically, examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, bisphenol A Inorganic cesium salts such as disodium salt, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt, cesium hydroxide, cesium carbonate, cesium hydrogen carbonate, cesium acetate,
Organic acid cesium salts such as cesium stearate; cesium alcoholates such as cesium methylate and cesium ethylate; cesium phenolate; phenol cesium salts such as bisphenol A cesium salt;

Specific examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, and calcium carbonate. , Barium carbonate, magnesium carbonate, strontium carbonate and the like. These compounds are used alone or in combination.

In the present invention, a basic compound may be used as a catalyst together with the above-mentioned alkali metal compound and / or alkaline earth metal compound. Such a basic compound is, for example, a nitrogen-containing basic compound which is easily decomposable or volatile at a high temperature, rarely remains in the final aromatic polycarbonate and does not adversely affect physical properties such as hue, and phosphonium hydroxy. And a basic boron compound. Specific examples include the following compounds.

Examples of the nitrogen-containing basic compound include ammonium hydroxides having an alkyl, aryl, araryl group and the like such as titramethylammonium hydroxide (Me ₄ NOH) and tetraethylammonium hydroxide (Et ₄ NOH), trimethylamine, triethylamine Secondary amines represented by R ₂ NH (where R is an alkyl group such as methyl and ethyl, and an aryl group such as phenyl and toluyl);
Primary amines represented by NH ₂ (wherein R is as defined above), imidazoles such as 2-methylimidazole and 2-phenylimidazole, iminocarboxylic acid derivatives such as sodium nitrilotriacetate or salts thereof, or ammonia , tetramethyl ammonium borohydride (Me ₄ NBH _4), basic salts such as tetrabutylammonium borohydride (Bu ₄ NBH ₄₎ and the like.

Examples of the phosphonium hydroxide compound include tetraethylphosphonium hydroxide, tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide, methyltriphenylphosphonium hydroxide, allyltriphenylphosphonium hydroxide and the like.

Of these, tetraalkylammonium hydroxide, tetrabutylphosphonium hydroxide and tetraphenylphosphonium hydroxide are preferably used.

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 boron, Hydroxides such as tributylbenzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, butyltriphenylboron, and the like;
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.

In the case of an alkali metal compound and / or an alkaline earth metal compound, the amount of the catalyst used is usually 1 × 10 ^-8 to 1 mol per mol of the aromatic diol compound.
It is used in an amount of × 10 ⁻⁴ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁵ mol. In the case of a basic compound, it is usually 1 × 10 ⁻ mol per 1 mol of the aromatic diol compound. ⁷ to 1 ×
It is used in an amount of 10 ^-1 mol, preferably 1 x 10 ^-6 to 1 x 10 ^-2 mol.

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 until a prepolymer having a viscosity average molecular weight in the range of 3,000 to 18,000 can be produced. However, a vertical stirring tank type polymerization tank is usually used. Wing, paddle wing, anchor wing, helical ribbon wing, double helical ribbon wing, full zone wing (manufactured by Shinko Pantech Co., Ltd.), Sun Meller wing (manufactured by Mitsubishi Heavy Industries, Ltd.), Max Blend wing (Sumitomo Heavy Industries, Ltd.) ), A twisted lattice blade (manufactured by Hitachi, Ltd.) or the like. The number of polymerization tanks is about 2 to 5 tanks.

FIG. 1 shows an example of an apparatus used to carry out the present invention. The polymerization in this step is performed with an inert gas,
For example, under a nitrogen gas atmosphere, for example, a molten mixture of bisphenol A as an aromatic diol compound and diphenyl carbonate as a carbonic acid diester compound is passed through the raw material introduction pipe 1 and the catalyst alkali metal compound and / or
Alternatively, an alkaline earth metal compound and / or a basic compound is supplied into the vertical polymerization tank 4 having the stirring blade 5 through the catalyst introduction pipe 2, and phenol produced as a by-product is removed from the by-product discharge pipe 3. Polymerization proceeds while 2-5 until the viscosity average molecular weight reaches 3,000-18,000
The vertical polymerization tanks 4, 4 ′, 4 ″ can be divided into smaller tanks to allow the polymerization to proceed continuously. The polymerization temperature during this period is 100 to 320 ° C., preferably 180 to 29 ° C.
In the range of 0 ° C., the reaction pressure ranges from normal pressure to 0.1 Torr.

Next, the viscosity average molecular weight of 3,
000-18,000, preferably 5,000-1
6,000 aromatic polycarbonate prepolymers are introduced into the horizontal uniaxial polymerization apparatus 17 and further subjected to a polycondensation reaction.

The horizontal uniaxial polymerization apparatus 17 is provided with an inlet 8 and an outlet 9 for the treatment liquid and an outlet 3 for volatile substances. In the polymerization apparatus 17, a hollow rotating body that constitutes one feature of the present invention is disposed. This hollow rotating body is mainly composed of a rotating shaft 1
0, discs 11 and 11 ′ provided at both ends of the polymerization apparatus 17, a plurality of hollow discs 13 having a central opening provided between the discs 11 and 11 ′, and discs 13
A plurality of flat blades 12 are provided between them.

The hollow rotor will be described more specifically. The rotating shaft 10 is inserted coaxially with the axis of the polymerization device 17 from outside at both ends in the longitudinal direction of the polymerization device 17. Disk 1 mounted almost perpendicular to this rotating shaft 10
A flat plate blade 12 is provided between 1 and 11 '. The flat blade 12 is preferably slightly bent so that one end thereof is L-shaped.
The angle α (0 ° <α) with respect to the rotation direction side of the outer tangent of 1 ′
<90 °), and the L-shaped one-end bent portion of the flat plate blade 12 is parallel to the axial center from the rear position to the axial center from the rear side with respect to the rotation direction. And with a slight gap. Further, the hollow partition disk 13 is installed substantially perpendicular to the flat plate blade 12, and the interval and the inner diameter thereof increase stepwise from the inlet 8 to the outlet 9 of the processing liquid. At the same time, the blade width of the flat blade 12 gradually decreases from the inlet 8 to the outlet 9 of the processing liquid. Phenol by-produced during the polycondensation reaction is discharged from the by-product discharge pipe 3.

The prepolymer supplied to the inlet at one end of the horizontal uniaxial polymerization apparatus 17 is scraped up along the inner wall of the apparatus by the rotating flat blades 12, and falls freely while forming a thin film in the middle of the scraping. Hollow partition disk 13
Are sequentially transferred in the direction of the outlet while passing through the opening. The amount of the polymer held up is 20 to 60%, preferably 30 to 5%, from the viewpoint of securing a space where a thin film can be sufficiently formed by free fall and improving the productivity of the apparatus.
It is controlled to be in the range of 0%.

L / D of the device (L: length in the device axial direction, D:
The inner diameter of the hollow partition disk 13 is about 2 to 10, and the partition interval and the inner diameter of the hollow partition disk 13 are from the inlet to the outlet in consideration of the plug flow property and the formation stability of the thin film according to the viscosity of the processing solution. For example, in the low-viscosity region where the viscosity of the treatment liquid is about 100 to 600 poise, the inner diameter is about (0.3 to 0.6) × the outer diameter. In the range of several thousand to 20,000 poise, in the high viscosity region,
A hollow disk having an opening with an inner diameter of about (0.6 to 0.9) x an outer diameter is used.

The flat blade has an acute angle of inclination with respect to the rotation direction side of the peripheral tangent of the end disk.
Preferably, it is attached at an inclination angle of 30 to 60 degrees, and the wing width is (0.8 to 0.8) with respect to the ring width d of the hollow disk.
1.2) Decrease stepwise so as to have a width of about × d. Decreasing the blade width has the effect of suppressing the adhesion and retention of the processing liquid on the flat plate blade due to the increase in the viscosity of the processing liquid, and facilitating the free fall of the scraped processing liquid. In addition, the flat blade is in a state in which one end on the rear side with respect to the rotation direction is slightly bent toward the axial direction. This has the effect of stabilizing the formation of the thin film of the scraped processing liquid. . further,
By providing slits in the flat blades, it is possible to promote the stirring and mixing action of the processing liquid present at the bottom in the apparatus. The number of flat blades is about 4 to 12, preferably 6
About 10 to 10 sheets.

FIG. 2 is a cross-sectional view of the hollow rotating body according to the present invention. The symbols A, B, C, D and E given in FIG. 2 are AA, BB, CC, D- in FIG.
The cross-sectional view along the line D and EE is shown, respectively. As the prepolymer in the polymerization device 17 advances in the downstream direction, the viscosity of the polymer also rises to the right as shown in FIG. In response to this, the hollow rotary body also has a larger inner diameter of the opening of the partition disk, as shown by symbols A to E in FIG. 2, and the interval between the partition disks has also increased as shown in FIG. Conversely, the width of the flat blades decreases stepwise as it proceeds downstream.

The clearance between the inner wall of the apparatus and the above-mentioned hollow rotator is 15 mm or less, preferably in the range of 2 to 8 mm.

The discs at both ends in the longitudinal direction of the apparatus preferably have the same shape as the adjacent hollow discs. Usually, the discs processed so as to be attached to the rotating shaft are used.

The polymerization in the horizontal uniaxial polymerization apparatus of the present invention is preferably performed under the following conditions. According to this condition,
Furthermore, a high molecular weight aromatic polycarbonate excellent in hue can be obtained at low cost and efficiently. The rotation speed of the hollow horizontal rotating body is 2 to 15 rpm, preferably 3 to 8 rpm.
The range of pm is good. The polymerization temperature is 240-350 ° C, preferably 260-320 ° C, more preferably 270-30.
A range of 0 ° C. is preferred. The pressure is controlled to be 3 Torr or less, preferably 1 Torr or less. The residence time is 10
A range of 120 minutes is preferred. Depending on the above polymerization conditions, the viscosity average molecular weight is usually 7,000 or more, preferably 9,000.
0 or more, and the resulting aromatic polycarbonate has a viscosity average molecular weight of 10,000 to 40,000, preferably 13,000 to 30,000, more preferably 15,000.
00 to 25,000. Further, within the above range of the viscosity average molecular weight, a plurality of the horizontal uniaxial polymerization apparatuses may be arranged and used in series.

[0041]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The obtained aromatic polycarbonate was analyzed by the following measurement method. (1) Viscosity average molecular weight Using a Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured and determined by the following equation. [Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83 (2) Hue (i) Production of Injection Molded Sheet Using an injection molding machine J100SS-2 (manufactured by Nippon Steel Works), a barrel temperature of 280 ° C. and gold were used. Under a condition of a mold temperature of 80 ° C., a sheet having a thickness of 3 mm and a side of 100 mm square was injection molded. (Ii) Hue For the injection molded sheet, the tristimulus value XYZ, which is the absolute value of the color, was measured with a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.), and YI, which is an index of the degree of yellowness, was obtained by the following relational expression. The value was calculated. YI = (100 / Y) × (1.28X−1.06Z) The larger the YI value, the more colored.

Example 1 In a nitrogen gas atmosphere, a mixture of bisphenol A and diphenyl carbonate in a fixed ratio (diphenyl carbonate / bisphenol A (molar ratio) = 1.040) was adjusted to a total of 401.064 mol / hour. At a flow rate of
1 was continuously supplied through a raw material introduction pipe into a first vertical stirring polymerization tank 4 having a capacity of 100 liters and controlled at 220 ° C. under a nitrogen atmosphere at 100 Torr under a nitrogen atmosphere of 100 Torr. 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 so that the time was 60 minutes. Simultaneously with the start of the supply of the raw material mixture, a 2% aqueous cesium carbonate solution was continuously supplied as a catalyst at a flow rate of 3.2 ml / hour (1 × 10 ⁻⁶ mol per mol of bisphenol A). The polymerization liquid discharged from the bottom of the tank is continuously used in the second and third (second: max blend blade, third tank: double helical ribbon blade) 100 L vertical stirring polymerization tank, and the main features of the present invention. Is continuously supplied to a fourth polymerization tank which is a horizontal uniaxial device having a capacity of 90 L, and the polymer discharged from the polymer outlet at the bottom of the fourth polymerization tank is subjected to devolatilization cooling,
Pelletized to obtain pellets. During the polymerization, the average residence time in each of the second, third and fourth polymerization tanks was 60 minutes, 60 minutes, and 4 minutes.
The liquid level was controlled so as to be 0 minutes, and phenol by-produced was also distilled off at the same time. The reaction conditions in the second to fourth polymerization tanks are respectively set in the second polymerization tank (240 ° C.,
15 Torr), third polymerization tank (280 ° C., 0.5 Torr)
r) In a fourth polymerization tank (290 ° C., 0.5 Torr), conditions were set to high temperature and low pressure as the reaction progressed. Also,
In the fourth polymerization tank, L / D = 4.0, and from one end on the prepolymer inlet side to 1/3 of the entire length of the apparatus, the inner diameter of six sheets (including a disk with a rotating shaft) = 0.55 X Hollow disks with outer diameters are arranged at approximately equal intervals, and
In the center of the apparatus up to / 3, there are three hollow disks with an inner diameter of 0.70 × outer diameter, and between 2/3 and the other end on the polymer outlet side, two (with a rotating shaft attached) Are included such that the hollow disks having an inner diameter of 0.80 × outer diameter are substantially equally spaced. The outer diameter of each of the partition disks was 295 mm, and the inner diameter of the device was 300 mm. The blade width of the flat blade is reduced in three steps so as to be substantially equal to the ring width of the hollow disk.
It was a sheet. The angle of inclination is 45 ° with respect to the rotation direction side of the outer tangent to the outer periphery of the disk. The gap between the plate and the flat blade was set to 2.5 mm. The viscosity average molecular weights of the polymers extracted from the third and fourth polymerization tanks at the time when each tank was stabilized stably were 10,800, 22,300, respectively. Further, the hue YI of the polymer obtained from the fourth polymerization tank was 1.2.

COMPARATIVE EXAMPLE 1 In the hollow rotary member of the fourth polymerization tank of Example 1, 16 hollow disks (including a disk for mounting a rotating shaft) having an inner diameter of 0.55 × an outer diameter were arranged in the longitudinal direction of the apparatus. Polymerization was performed under the same polymerization conditions as in Example 1 except that the blades were arranged at substantially equal intervals, and were replaced with a structure in which the blade width of the flat blade was uniformly arranged so as to be substantially equal to the ring width of the hollow disk. The operation was carried out, but the phenomenon of stagnant circulation of the polymer occurred in the region near the polymer outlet of the fourth polymerization tank. The operation could not be continued for the predetermined residence time. In addition, the viscosity average molecular weight of the polymer obtained during the continuation of operation is from 19,000 to 24,000.
In the range of 0, the hue YI was in the range of 1.1 to 2.3, and stable quality could not be secured.

Comparative Example 2 In the hollow rotating body of the fourth polymerization tank of Example 1, seven hollow disks (including a disk for mounting a rotating shaft) having an inner diameter = 0.80 × outer diameter were used in the longitudinal direction of the apparatus. Polymerization was performed under the same polymerization conditions as in Example 1 except that the blades were arranged at substantially equal intervals, and were replaced with a structure in which the blade width of the flat blade was uniformly arranged so as to be substantially equal to the ring width of the hollow disk. The operation was performed. The viscosity average molecular weights of the polymers withdrawn from the third and fourth polymerization tanks at the time when each tank was stabilized stably were 10,8, respectively.
The polymerization rates were 00, 16, and 100, and a decrease in the polymerization rate in the fourth polymerization tank was observed. The hue YI of the polymer was 1.1.
Met.

Comparative Example 3 A polymerization operation was carried out under the same polymerization conditions as in Example 1 except that the fourth polymerization tank was replaced with a horizontal biaxial type polymerization tank. The viscosity average molecular weights of the polymers extracted from the third and fourth polymerization tanks at the time when each tank was stabilized stably were 10,800 and 22,800, respectively. The hue YI of the polymer obtained from the fourth polymerization tank was 1.
It was 8.

[0046]

According to the production of the aromatic polycarbonate according to the present invention, a high molecular weight aromatic polycarbonate having an excellent hue can be efficiently produced at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an apparatus used to carry out the present invention.

FIG. 2 is a cross-sectional view of a hollow rotating body according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 raw material introduction pipe 2 catalyst introduction pipe 3 by-product discharge pipe 4, 4 ′, 4 ″ vertical polymerization tank 8 inlet 9 outlet 10 rotating shaft 11, 11 ′ disk 12 flat plate blade 13 hollow partition disk 17 horizontal type Uniaxial polymerization equipment

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsushige Hayashi 2-16-16 Hinagahigashi, Yokkaichi City, Mie Prefecture Inside of Mitsubishi Gas Chemical Co., Ltd. Yokkaichi Plant (72) Inventor Yuji Takeda 2 Higenagahigashi, Yokkaichi City, Mie Prefecture -4-16 Inside the Yokkaichi Plant of Mitsubishi Gas Chemical Co., Ltd.

Claims (3)

[Claims] 1. A method for producing an aromatic polycarbonate by subjecting an aromatic diol compound and a carbonic acid diester to a transesterification reaction, wherein the aromatic diol compound and the carbonic acid diester are subjected to a polycondensation reaction to obtain a viscosity average molecular weight of 3,0.
After the production of the prepolymer of 100 to 18,000, the prepolymer is fed to a horizontal polymerization apparatus having a processing liquid inlet, an outlet and a volatile matter discharge port, and externally provided at both ends in the longitudinal direction of the polymerization apparatus. A rotating shaft inserted coaxially with the axis of the polymerization apparatus, and disks attached substantially perpendicular to the rotating shaft.
A plurality of flat blades slightly bent so as to form a letter shape are formed such that the flat blades have an inclination angle of α (0 ° <α <90 °) with respect to the rotation direction side of the outer peripheral tangent of the disk. To
Further, the flat blade is provided so that one end bent portion is directed toward the axis from a position rearward with respect to the rotation direction, and a slight gap is provided between the flat surface and the inner wall surface of the polymerization apparatus. An almost vertically hollow partition disk is connected and arranged so as to gradually increase the interval and the inner diameter from the inlet to the outlet of the processing liquid, and the blade width of the flat blade is reduced stepwise. A method for producing an aromatic polycarbonate, comprising introducing the prepolymer into a horizontal uniaxial polymerization apparatus provided with a hollow rotating body having a structure, and further subjecting the prepolymer to a polycondensation reaction. 2. The rotation speed of the hollow rotator in the horizontal uniaxial polymerization apparatus is 2 to 15 rpm, the temperature is 240 to 350 ° C., the pressure is 3 Torr or less, and the residence time is 10 to 1 pm.
The method for producing an aromatic polycarbonate according to claim 1, wherein the polycondensation reaction is performed in a range of 20 minutes. 3. The method for producing an aromatic polycarbonate according to claim 1, wherein an aromatic polycarbonate having a higher molecular weight and a viscosity average molecular weight of 10,000 to 40,000 than the prepolymer is obtained.