JPH09286850A - Production of aromatic polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-molecular-weight aromatic polycarbonate resin having excellent hue. SOLUTION: This resin is produced by transesterifying an aromatic diol compound with a carbonic diester in the preliminary polycondensation step 1 using an upright reactor 4 with an agitator to produce a first prepolymer, converting the first prepolymer into a second prepolymer in the prepolycondensation step 2 using an upright reactor 4 with an agitator consisting of a double-helical ribbon blade, leading the second prepolymer to a horizontal reactor 7 in which grid type agitating blades 8 each of which is formed by juxtaposing two rotary trunnion and connecting a plurality of rodlike rectangular frames to each trunnion in the proximity of the inside of the mating blade so as to mesh with each other, and subjecting the second prepolymer to a polycondensation reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polycarbonate by a transesterification reaction, and more specifically, to produce an aromatic polycarbonate having improved heat resistance from an aromatic diol compound and a carbonic acid diester by a melt polycondensation reaction. It is about how to do it.

[0002]

2. Description of the Related Art In recent years, aromatic polycarbonates have been used as carbonated beverage bottles, electronic substrates (CD substrates), transfer belts as engineering plastics having excellent mechanical properties such as impact resistance, heat resistance and transparency. It is widely used in many fields.

As a method for producing this aromatic polycarbonate, a so-called phosgene method in which an aromatic diol such as bisphenol and phosgene are reacted by an interfacial polycondensation method has been industrialized. However, this phosgene method
It has been pointed out that phosgene, which is toxic to the human body, must be used and that a large amount of by-produced sodium chloride is mixed into the produced polymer, causing problems such as corrosion when used in electronic devices.

Further, a method of obtaining an aromatic polycarbonate by transesterification of an aromatic diol compound and a carbonic acid diester has long been known as a so-called melting method or non-phosgene method. The non-phosgene method is said to have the advantages that the above-mentioned various problems of the phosgene method do not occur and that the aromatic polycarbonate can be produced at a lower cost. However, since the non-phosgene method is a bulk polymerization reaction method, the viscosity of the reaction mixture increases as the molecular weight of the aromatic polycarbonate increases, making it difficult to efficiently remove by-products such as phenol from the reaction mixture in the latter stage of the polymerization process. There was a problem that

In order to solve this problem, a two-step polymerization method is generally known in which a prepolymer having a relatively low molecular weight is produced in a prepolymerization step and then a high molecular weight is obtained in a postpolymerization step. As the post-polymerization step, there are a method using a horizontal polymerization apparatus compatible with high viscosity, a method of performing solid-phase polymerization, and the like. However, a method using a horizontal polymerization apparatus can obtain a polymer with high productivity and is industrially used. Used as an advantageous method. In such a two-step polymerization method, various proposals have been made to use an apparatus having a special stirring type. For example, in JP-A-4-142329, in a method for producing an aromatic polycarbonate by melt-polycondensing an aromatic diol compound and a bisaryl carbonate by a transesterification method, a polycondensation reaction is carried out in a tank reactor. After that, using at least one or more paddle type self-cleaning twin-screw extruders, the viscosity average molecular weight of 12,000-
A process for obtaining 60,000 aromatic polycarbonates is disclosed.

However, the application of the paddle type self-cleaning twin-screw extruder to the final manufacturing process, which is a high-viscosity treatment area, is a high-shearing type stirring blade, so that the stirring heat generation is large and the hue of the aromatic polycarbonate obtained is high. There was a problem that it worsens. In addition, JP-A-7-3309
No. 10 discloses a method for continuously polymerizing a polycondensation type polymer, which has a rotary shaft at the upper part inside the container, and a plurality of rectangular frame-shaped stirring blades are connected to the rotary shaft to scrape the inner wall of the container. A polymerization method is characterized in that a polycarbonate prepolymer having an average molecular weight of 5,000 to 10,000 is polycondensed using a stirrer to obtain an intermediate polymer having an average molecular weight of 10,000 to 20,000. Has been described. However, in the above-mentioned molecular weight range, the viscosity of the treatment liquid is about several hundred to several thousand poises, and the application of this apparatus in this molecular weight region is not always necessary for the surface renewal property to the gas-liquid interface due to the stirring action of the polymerization liquid in the tank. It is not excellent, and there is a problem that a long residence time is required to reach a predetermined molecular weight, and the hue of an aromatic polycarbonate obtained by a long heat history is deteriorated.

Further, in the method for producing an aromatic polycarbonate disclosed in Japanese Patent Laid-Open No. 2-153925, polymerization is carried out using a horizontal polymerization apparatus having a stirring blade vertically attached to a horizontal rotary shaft. For,
Inevitably, the polymer is likely to stay in a portion such as a horizontal rotary shaft that does not directly contribute to stirring, which causes coloring of the obtained polymer and generation of unnecessary gel. Also, JP-A-63-
Japanese Patent No. 23926 discloses a production example of a polycarbonate using an extruder polymerization apparatus in which a screw and a paddle are combined, but again, the retention of the polymer easily occurs in the discontinuous portion of the blade, which causes coloring and deterioration of physical properties. There was a problem.

[0008]

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

[0009]

The present invention relates to a method for producing an aromatic polycarbonate resin by subjecting an aromatic diol compound and a carbonic acid diester to a transesterification reaction, which comprises: (1) pre-polycondensation step: aromatic diol compound A molten mixture of carboxylic acid and a carbonic acid diester is fed into a vertical stirring reaction apparatus, and a polycondensation reaction of the mixture is performed to obtain a viscosity average molecular weight of 3,0.
After producing the first prepolymer of 00 to 10,000, (2) pre-polycondensation step: the first prepolymer obtained in the step (1) is a vertical stirring reaction apparatus equipped with a double helical ribbon blade. And a polycondensation reaction is carried out in the same reactor to obtain a second prepolymer having a viscosity average molecular weight of 10,000 to 20,000. (3) Post-polycondensation step: the second prepolymer of the step (2). The horizontal type container has a longitudinal end in the longitudinal direction of the container, an inlet and an outlet for the liquid to be treated at the lower end and the upper end, respectively, and two rotating ear shafts at both longitudinal ends inside the container. Are arranged side by side, and a plurality of rod-shaped rectangular frames are connected to each of the rotating shafts to form a lattice type stirring blade, and the stirring blades rotate close to the inside of the mating stirring blade so that they mesh with each other. To a horizontal reactor to carry out a polycondensation reaction, To obtain an aromatic polycarbonate resin having a higher molecular weight than the second prepolymer and having a viscosity average molecular weight of 15,000 to 40,000. .

[0010]

The prepolymer and the polymer are sufficiently stirred, the reaction rate is fast, the aromatic polycarbonate having a higher molecular weight and less coloring can be produced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing an aromatic polycarbonate according to the present invention will be specifically described below. 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 is a compound represented by the general formula (1).

[0012]

Embedded image

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

Some representative examples are, for example, bis (4-hydroxydiphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl). propane,
2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5
-Dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromo) propane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) cyclohexane, etc. Bisphenol; 4,4'-dihydroxybiphenyl-3,
Biphenols such as 3 ', 5,5'-tetramethyl-4,4'-biphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide,
Bis (4-hydroxyphenyl) ether, bis (4-
Hydroxyphenyl) ketone and the like. Of these, 2,2-bis (4-hydroxyphenyl) propane is preferable.

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. Further, for the purpose of further improving the thermal stability and hydrolysis resistance of the aromatic polycarbonate produced, monovalent compounds such as pt-butylphenol and p-cumylphenol are used for the purpose of sealing the hydroxyl terminal. Phenols can also be used.

Carbonic acid diester; examples of the carbonic acid diester include dimethyl carbonate, diphenyl carbonate,
Ditolyl carbonate, bis (4-chlorophenyl) carbonate, bis (2,4,6-trichlorophenyl)
There are carbonates and the like. These carbonic acid diester compounds are generally used in excess with respect to 1 mol of the aromatic diol compound, and are used in an amount of 1.01 to 1.30 mol, preferably 1.02 to 1.20 mol. Is desirable.

Transesterification catalyst: In the melt polycondensation reaction of 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, or a phosphonium salt is preferably used. As such an alkali metal compound and an alkaline earth metal compound, specifically, ,
Preference is given to organic hydrochloric acid, inorganic hydrochloric acid, acid compounds, hydroxides, hydrides or alcoholates of alkali metals and alkaline earth metals.

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, and bisphenol A. Disodium salt, dipotassium salt, dilithium salt, sodium salt, potassium salt, lithium salt of phenol, cesium hydroxide, cesium carbonate, inorganic cesium salt such as cesium hydrogen carbonate, cesium acetate,
Examples thereof include organic acid cesium salts such as cesium stearate, alcohol cesium salts such as cesium methylate and cesium ethylate, cesium phenolate, and phenolic cesium salts such as cesium salt of bisphenol A.

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 can be used as a catalyst together with the above-mentioned alkali metal compound and / or alkaline earth metal compound. Such basic compounds include, for example, nitrogen-containing basic compounds and phosphonium hydroxy compounds which are easily decomposable or volatile at high temperatures, rarely remain in the final aromatic polycarbonate, and do not adversely affect physical properties such as hue. And specifically, the following compounds.

Examples of the nitrogen-containing basic compound include ammonium hydroxides having an alkyl, aryl, araryl group and the like such as tetramethylammonium 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. When a basic compound is used as the catalyst, the basic compound is usually 1 × 10 ⁻⁶ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁵ to 1 × with respect to 1 mol of the aromatic diol compound. Used in an amount of 10 ^-2 mol.

Aromatic Polycarbonate Production Process: In the present invention, the polycondensation reaction of an aromatic diol compound and a carbonic acid diester is carried out using a vertical stirring reactor and a horizontal reactor as shown in FIG. It is carried out through steps. (1) Preliminary polycondensation step: A molten mixture of an aromatic diol compound and a carbonic acid diester is fed into a vertical stirring reaction apparatus, and a polycondensation reaction of the mixture is performed to obtain a viscosity average molecular weight of 3,0
After producing the first prepolymer of 00 to 10,000, (2) pre-polycondensation step: introducing the first prepolymer obtained in the above step into a vertical stirring reaction apparatus equipped with a double helical ribbon blade, A polycondensation reaction is carried out in a reactor to obtain a second prepolymer having a viscosity average molecular weight of 10,000 to 20,000. (3) Post-polycondensation step: The second prepolymer obtained in the step (2) is obtained. The horizontal container has an inlet, an outlet, and an outlet for volatile matter of the liquid to be treated at one end lower part, the other end lower part, and upper part in the longitudinal direction, and two rotating ear shafts are juxtaposed at both longitudinal end parts inside the container. Then, a plurality of rod-shaped rectangular frames are connected to each of the rotating ear shafts to form a grid-type stirring blade, and a horizontal reaction that rotates close to the inside of the other stirring blade so that the stirring blades mesh with each other. Bring it into the equipment and perform polycondensation reaction (2)
To obtain an aromatic polycarbonate resin having a higher molecular weight than the second prepolymer and having a viscosity average molecular weight of 15,000 to 40,000. In the above, in the pre-polycondensation step of (1), if a vertical stirring reaction apparatus equipped with the double helical ribbon blade used in the pre-polycondensation step of (2) is used as the vertical stirring reaction apparatus, at least two steps are required. It can be carried out.

FIG. 1 shows a flow sheet of the present invention. In the figure, 1 is a raw material introduction pipe, 2 is an ester conversion catalyst introduction pipe, 3
Is a by-product discharge pipe, 4, 4'is a vertical reactor, 5 is a stirring blade, 6 is a double helical ribbon blade, 7 is a partial horizontal sectional view of a horizontal reactor, 8 is a lattice blade, and 9 is a first Prepolymer, 10 is a second prepolymer, 11 is a final product polymer, 12 is a driving machine, and 13 is a shaft seal. Horizontal reactor 7
Has an inlet (20) and an outlet (21) for the second prepolymer at the bottoms of both ends, and a volatile matter discharge port 3 at the top (both are not shown in FIG. 1). FIG.
FIG. 3 is an enlarged cross-sectional view of a vertical reactor 4 ′ equipped with a double helical ribbon blade 6. In the figure, 14 is a raw material (prepolymer) introducing pipe, 15 is a rotating shaft, 16 is a screw portion for feeding out the prepolymer, and 17 is a prepolymer discharge port. FIG. 3 is a cross-sectional view taken along the line AA of the horizontal reactor 7 in FIG. FIG. 4 is a perspective view of the lattice vanes 8 in the horizontal reactor.

(1) Pre-polycondensation step: In the present invention, a reaction apparatus 4 ′ equipped with a double helical ribbon blade is used after the viscosity average molecular weight of the produced prepolymer becomes 3,000 or more. Any device can be used until the average molecular weight is reached. For example, turbine blades, paddle blades, anchor blades, helical ribbon blades, double helical ribbon blades, Maxblend blades shaped along the inner surfaces of the lower and side walls of the tank (Chemical Engineering Review, 911 of the fifth revised edition).
Page; Maruzen publication) etc. can be used. Moreover, the number of reaction tanks is about 2 to 5. The reaction in the first stage pre-polycondensation reactor is carried out under an atmosphere of an inert gas such as nitrogen gas, for example, 2,2-bis (4-hydroxyphenyl) propane as an aromatic diol compound and diphenyl carbonate as a carbonic acid diester. A vertical mixture provided with the stirring blade 5 through a raw material introduction pipe 1 and a catalyst alkali metal compound and / or alkaline earth metal compound and / or basic compound through a catalyst introduction pipe 2. To the mold stirring reactor 4,
The reaction proceeds while removing by-products from the by-product discharge pipe 3. Until the viscosity average molecular weight reaches 3,000 to 10,000, it is also possible to divide the reactors 4 and 4 into about two to five tanks to continuously carry out the polymerization. The reaction temperature during that period is 100 to 300 ° C., preferably 180 to 300 ° C.
In the range of 280 ° C., the reaction pressure is in the range of atmospheric pressure to 1 Torr.

(2) Pre-polycondensation step: Next, the aromatic polycarbonate resin (first prepolymer) having a viscosity average molecular weight of 3,000 to 10,000, preferably 5,000 to 8,000, obtained by the above operation is added. It is supplied to a vertical reactor 4 ′ equipped with a double helical ribbon blade 6, and the reaction is further promoted while distilling out by-produced phenol out of the system. The dimension specifications of the double helical ribbon blade are clearance (d / D)
About 0.85-0.95, blade pitch (L / d) is 0.95
Approximately 1.05, which is almost the same as the blade diameter, and the ribbon blade width (b
/ D) is preferably about 0.08 to 0.12. A gas phase portion 18 is present in the upper portion of the vertical reactor 4 ', and the structure is such that the by-produced phenol can be discharged 3. Also,
It is preferable that the feed port 14 for the first prepolymer is located in the liquid phase portion on the side wall of the apparatus and the outlet port 17 is located in the bottom portion of the tank.
Further, it is preferable that a screw type polymer discharger 16 is introduced into the outlet at the bottom of the tank. The reaction temperature is 200 to 320 ° C., preferably 240.
In the range of ~ 300 ° C, the reaction pressure is 10 Torr or less,
It is preferably controlled to 1 Torr or less. Further, the blade rotation speed is about 10 to 100 rpm, and the polymerization time can be shortened by setting the rotation speed to a high speed such that the processing liquid does not co-rotate. The reaction time is in the range of 30 to 120 minutes, and the viscosity average molecular weight is usually increased by 5,000 or more, preferably 7,000 or more by this polymerization. The second prepolymer obtained has a viscosity average molecular weight of 10,000 to 20,000, preferably 13,000 to 18,000.

(3) Post-polycondensation step: Subsequently, the second prepolymer obtained by the above-mentioned reaction operation is added to the substantially horizontal container 1
9 has an inlet 20, an outlet 21, and a volatile matter discharge port 3 for the liquid to be treated, respectively at one end lower part, the other end lower part and the upper part in the longitudinal direction, and two rotary shafts 8a at both longitudinal end parts inside the container,
8b are arranged side by side, and a plurality of rod-shaped rectangular frames 8 and 8 are connected to each of the rotating shafts to form a lattice type stirring blade, and the stirring blades are in close proximity to each other so that they mesh with each other. Then, it is supplied to a rotating horizontal reactor, and the reaction is further advanced while distilling off the by-product phenol. The polymer is supplied from the liquid phase portion at one end of the horizontal reactor, preferably from the lower portion 20 at one end, and discharged by a screw type discharging device provided at the lower end of the other end. A gas phase section 22 and a discharge line 3 for distilling off by-produced phenol from a thin film-shaped treatment liquid formed by stirring are provided in the upper part of the apparatus. Further, the shape of the lower part of the apparatus is preferably a so-called inverted heart shape along the radius of curvature of the rotating rod-shaped rectangular frames 8 and 8 in order to eliminate the dead space of the processing liquid (see FIG. 3).

The dimension ratio of vertical 8'to horizontal 8 "of the rod-shaped rectangular frame 8 is 1
It is preferable that adjacent rectangular frames are connected to each other at a phase angle of 90 ° so that the stirring blades are shortened in the connection direction (polymer flow direction). The number of connected stages is about 4 to 12. Further, these two stirring blades rotate in different directions at the same speed so as to approach each other and scrape up the other side from below. The rotation speed is about 3 to 30 rpm. The reaction temperature is 200 to 320 ° C., preferably 240 to 300 ° C.
And the reaction pressure is 10 Torr or less, preferably 1
Control below Torr. The reaction time is in the range of 30 to 120 minutes, and the viscosity average molecular weight is usually 3,000 by this polymerization.
Increase by 0 or more, preferably by 5,000 or more.

The aromatic polycarbonate resin discharged from the horizontal reactor 7 has a viscosity average molecular weight of 15,000 to
40,000, preferably 20,000 to 35,000
The polymer has a high hue of YI of 1.8 or less and a good hue, and is pelletized and recovered after deaeration and cooling. Aromatic polycarbonate resin 1 recovered at this time
1, 40 to 100 ppm of diphenyl carbonate,
2,2-bis (4-hydroxyphenyl) propane is 1
0 to 20 ppm and phenol of about 5 ppm or less remain.

The aromatic polycarbonate resin obtained in the present invention contains the usual heat resistance stabilizer, ultraviolet absorber, mold release agent, antistatic agent, slip agent, antiblocking agent, lubricant, antifogging agent, natural oil, synthetic oil. Additives such as wax, organic fillers, and inorganic fillers may be added. Such additives can be added to the aromatic polycarbonate resin in a molten state, or the aromatic polycarbonate resin once pelletized can be remelted and added. The remelting is preferably performed in an inert gas atmosphere.

The steps of the present invention can be carried out by a continuous method, a batch method, a combination of continuous and batch methods, and any method may be used.

[0033]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The aromatic polycarbonate resin obtained by the present invention was analyzed by the following measuring method. (1) Viscosity average molecular weight Using an Ubbelohde viscometer, the intrinsic viscosity [η] at 20 ° C. in methylene chloride was measured and calculated from the following formula. [Η] = 1.23 × 10 ⁻⁴ × (Mv) ^0.83 (2) Hue 10% methylene chloride solution with a diameter of 25 mm and a height of 55 mm
The tristimulus value XYZ, which is the absolute value of the color, is measured with a color tester (SC-1-CH manufactured by Suga Test Instruments Co., Ltd.) and the YI value, which is an index of yellowness, is calculated by the following relational expression. Was calculated. YI = 100 / Y (1.28X-1.06Z) The larger the YI value, the more the coloring.

Example 1 In a nitrogen gas atmosphere, bisphenol A and diphenyl carbonate were mixed and prepared at a constant ratio (diphenyl carbonate / bisphenol A (molar ratio) = 1.050). At the flow rate of
1 equipped with the Maxblend blade shown in FIG. 1 through the raw material introduction pipe, and the capacity 1 controlled at 210 ° C. under normal pressure and nitrogen atmosphere.
It is continuously fed into the first vertical stirring reaction tank of 00 liters, and the liquid level is kept constant while controlling the valve opening provided in the polymer discharge line at the bottom of the tank so that the average residence time is 30 minutes. It was At the same time when the supply of the above raw material mixture was started, 3.2 ml / hour of a 2% cesium carbonate aqueous solution was used as a catalyst (1 x 1 mol of bisphenol A).
It was continuously fed at a flow rate of 10 ⁻⁶ mol). The polymerization liquid (prepolymer) discharged from the bottom of the tank is
It is continuously and continuously supplied to a vertical stirring reaction tank having a capacity of 100 liters equipped with 4,4 Maxblend blades and a fourth vertical stirring reaction tank 4'having a capacity of 100 liters equipped with a double-helical ribbon blade, and the fourth reaction The second prepolymer withdrawn from the bottom of tank 4'was pelletized after cooling. During the reaction, the liquid level is controlled by adjusting the valve opening degree provided in the prepolymer discharge line at the bottom of the tank so that the average residence time of each of the second to fourth reaction tanks is 60 minutes, and At the same time, the by-product phenol was distilled off.
The reaction conditions in the second to fourth reaction tanks are the second reaction tank (210 ° C., 100 Torr, 110 rpm) and the third reaction tank, respectively.
Reaction tank (240 ° C, 15 Torr, 75 rpm), 4th
In a reaction tank (280 ° C, 0.5 Torr, 25 rpm),
As the reaction progressed, conditions were set to high temperature, high vacuum, and low stirring speed. The dimension specifications of the double helical ribbon blade are clearance (d / D) 0.90, blade pitch (L / d) 1.00,
The ribbon blade width (b / D) was 0.10. The viscosity average molecular weights of the prepolymers extracted from the third and fourth reaction tanks were 6,200 and 16,100, respectively, and the total average residence time was 3.5 hours. Next, while melting the second prepolymer pellets obtained by the above operation by a single-screw extruder controlled at 280 ° C., the temperature was 290 ° C. and 0.5 T.
6 kg in a horizontal reactor 7 (“lattice blade polymerization machine” (trade name) manufactured by Hitachi, Ltd.) shown in FIGS. 1, 3 and 4 having a volume of 27 liters controlled to a rotation speed of 10 rpm.
/ Hr is continuously supplied, and the number of rotations of the extraction screw provided in the polymer discharge part of the horizontal reactor is adjusted so that the average residence time is 60 minutes. Was kept constant. From the start of the prepolymer supply, continuous operation was performed for about 4 hours until the quality of the discharged polymer 11 did not change with time.
The obtained aromatic polycarbonate resin had a viscosity average molecular weight of 30,100 and a hue YI of 1.5.

Comparative Example 1 The same procedure as in Example 1 was repeated except that the double helical ribbon blade 6 of the fourth vertical stirring reactor 4'was replaced with a Maxblend blade, and an aromatic polycarbonate resin was used. Obtained. The viscosity average molecular weight of the polymer at the inlet and outlet of the fourth vertical stirring tank was 6,200 and 12, respectively.
200, and the viscosity average molecular weight of the aromatic polycarbonate resin obtained from the horizontal reactor was 27,30.
0, and hue YI was 1.6.

Comparative Example 2 In Comparative Example 1, except that the average residence time in the fourth vertical stirring reaction tank 4 ′ equipped with a Maxblend blade was set to 1.5 hours in order to raise the viscosity average molecular weight to the same value as in Example, a comparison was made. The same reaction conditions as in Example 1 were carried out to obtain an aromatic polycarbonate resin. The viscosity average molecular weights of the polymer at the inlet and outlet of the fourth vertical stirring tank are 6,200 and 15,70, respectively.
Further, the viscosity average molecular weight of the aromatic polycarbonate resin obtained from the horizontal reactor was 29,800, but the hue YI was 2.3 and a decrease in hue was observed as compared with Example 1.

Comparative Example 3 In Example 1, the horizontal reactor 7 was replaced with a self-cleaning twin-screw reactor (“SCR” (trade name) manufactured by Mitsubishi Heavy Industries, Ltd.) having a capacity of 2 liters, and the average residence time was 6
An aromatic polycarbonate resin was obtained under the same reaction conditions as in Example except that the supply rate of the aromatic polycarbonate prepolymer pellets was set to 0 minute so as to be 1 Kg / Hr. The viscosity average molecular weight of the aromatic polycarbonate resin obtained from this horizontal reactor was 31,900, and the hue YI was 3.
It was 8.

Comparative Example 4 In Example 1, the prepolymer withdrawn from the fourth vertical stirring reaction tank 4'was replaced by a lattice blade polymerization machine, and subsequently the fourth polymer was used.
When the reaction was continued by continuously supplying it to the fifth vertical stirring reaction tank equipped with the double helical ribbon blade under the same specifications and the same reaction conditions as the vertical reaction tank, the polymer was started to be supplied to the fifth reaction tank and the reaction was continued. After 60 minutes, the stirring motor stopped tripping,
It became impossible to continue the reaction.

Comparative Example 5 Aromatic polycarbonate was prepared under the same reaction conditions as in Example 1 except that the double helical ribbon blade of the fourth vertical stirring reactor 4'was replaced with a single helical ribbon blade. A resin was obtained. The viscosity average molecular weight of the polymer at the inlet and outlet of the fourth vertical stirring tank was 6,20, respectively.
0 and 9,600, and the viscosity average molecular weight of the aromatic polycarbonate resin obtained from the horizontal reactor is 2
The hue was 1,800 and the hue YI was 1.4. When using a single helical ribbon blade, it is difficult to obtain a high molecular weight aromatic polycarbonate.

[0040]

According to the method for producing an aromatic polycarbonate resin according to the present invention, an aromatic polycarbonate resin having an excellent hue and a high molecular weight can be obtained.

[Brief description of drawings]

FIG. 1 is a flow sheet diagram of the manufacturing method of the present invention.

FIG. 2 is a cross-sectional view showing a vertical stirring reaction device equipped with a double helical ribbon blade.

FIG. 3 is a cross-sectional view taken along the line AA of the horizontal reactor in FIG.

FIG. 4 is a perspective view of a lattice type stirring blade of the horizontal reactor.

[Explanation of symbols]

 1 Raw Material Introducing Tube 4 Vertical Reactor 5 Stirring Blade 6 Double Helical Ribbon Blade 7 Horizontal Reactor 8 Lattice Stirring Blade 9 1st Prepolymer 10 2nd Prepolymer 11 Polycarbonate Resin 14 1st Prepolymer Inlet 17 2nd Pre Polymer outlet 18 Gas phase part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushige Hayashi 2-4-16 Hinagahigashi, Yokkaichi-shi, Mie Sanryo Gas Chemicals Co., Ltd. Yokkaichi Plant (72) Inventor Yuji Takeda Hinagahigashi, Yokkaichi-shi, Mie 2-4-16 Sanryo Gas Chemical Co., Ltd. Yokkaichi Plant

Claims (2)

[Claims] 1. A method for producing an aromatic polycarbonate resin by subjecting an aromatic diol compound and a carbonic acid diester to a transesterification reaction, which comprises: (1) a prepolycondensation step: a molten mixture of an aromatic diol compound and a carbonic acid diester; The mixture was fed into a vertical stirring reactor to carry out a polycondensation reaction of the mixture to obtain a viscosity average molecular weight of 3,0.
After producing the first prepolymer of 00 to 10,000, (2) pre-polycondensation step: the first prepolymer obtained in the step (1) is a vertical stirring reaction apparatus equipped with a double helical ribbon blade. To a second prepolymer having a viscosity average molecular weight of 10,000 to 20,000 by performing a polycondensation reaction in the same reactor, and (3) post-polycondensation step: the second polycondensation step of the above step (2). 2 Prepolymer has an inlet, an outlet, and a volatile matter discharge port for the liquid to be treated at one end lower part, the other end lower part, and upper part of the horizontal container in the longitudinal direction, and two rotations are made at both longitudinal ends of the container. The shafts are arranged side by side, and a plurality of rod-shaped rectangular frames are connected to each of these rotating shafts to form a grid-type stirring blade, which is placed close to the inside of the other stirring blade so that the stirring blades mesh with each other. Guided into the rotating horizontal reactor to carry out the polycondensation reaction. Wherein (2) a higher molecular weight than the second prepolymer, process for producing an aromatic polycarbonate resin, characterized in that the viscosity-average molecular weight is obtained aromatic polycarbonate resins 15,000 to 40,000. 2. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the vertical stirring reaction tank used in the prepolycondensation step is a vertical stirring reaction tank equipped with a Maxblend blade.