JPH08239465A - Production of aromatic polycarbonate resin - Google Patents

Abstract

PURPOSE: To obtain a high-quality aromatic polycarbonate resin excellent in hue, flow, heat resistance, hydrolysis resistance, etc., by transesterifying an aromatic dihydroxy compound with a diaryl carbonate in a specified manner. CONSTITUTION: A molten mixture of an aromatic dihydroxy compound with a diaryl carbonate is fed into a vertical/reactor with a mixer, and the mixture is polycondensed to produce a prepolymer having a terminal hydroxyl concentration of 1-40mol% based on the total terminal groups and having a viscosity- average of 3000-25000. The molecular weight of this prepolymer is increased by treating it in a horizontal twin-screw reactor under conditions including a temperature of 250-350 deg.C, a residence time of 10min or above and a hold-up of the prepolyer of 5-95% of the effective volume of the reactor. Thus, an aromatic polycarbonate having a terminal hydroxyl concentration of 30mol% or below based on the total terminal groups and a viscosity-average molecular weight of 14,000-60,000 can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an aromatic polycarbonate resin. More specifically, a high-quality aromatic polycarbonate resin having an excellent color tone, heat resistance and hydrolysis resistance is prepared by a transesterification method (melting method).
The present invention relates to a method of manufacturing with high productivity.

[0002]

2. Description of the Related Art Aromatic polycarbonate resins have excellent impact resistance as engineering plastics,
It is widely used for applications that take advantage of dimensional stability and transparency, such as optical disk substrates, carriages, and lenses.
As an industrial production method, an interfacial method in which a dihydroxydiaryl compound such as bisphenol is reacted with phosgene, or a transesterification method in which a dihydroxydiaryl compound such as bisphenol and a carbonic acid diaryl ester such as diphenyl carbonate are reacted in a molten state (melting Law) is known.

In general, as a method for obtaining a high molecular weight polymer, a two-step polymerization method is known in which a relatively low molecular weight prepolymer is produced in a prepolymerization step and then a high molecular weight is obtained in a postpolymerization step. There is. 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.

However, in the method for producing an aromatic polycarbonate disclosed in Japanese Patent Application Laid-Open No. 2-153925, polymerization is carried out by using a horizontal polymerization apparatus having a stirring blade vertically attached to a horizontal rotary shaft. Therefore, the polymer inevitably tends to stay in a portion such as a horizontal rotary shaft that does not directly contribute to stirring, and coloring of the obtained polymer or generation of unnecessary gel occurs. Further, Japanese Patent Application Laid-Open No. 63-23926 discloses an example of producing a polycarbonate using an extruder polymerization apparatus in which a screw and a paddle are combined. However, retention of the polymer also occurs in the discontinuous portion of the blade. However, there was a problem of coloring and deterioration of physical properties.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a high quality aromatic polycarbonate resin having excellent color tone, fluidity, heat resistance, hydrolysis resistance and the like with high productivity. .

[0006]

The present invention provides a method for producing an aromatic polycarbonate resin by a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diaryl ester, which comprises a prepolycondensation step: an aromatic dihydroxy compound and a carbonic acid diaryl ester. The molten mixture of and is fed into a rigid stirring reaction tank, and polycondensation reaction of the mixture is performed to obtain a viscosity average molecular weight of 3,
000 to 25,000, the terminal hydroxyl group concentration is 1 in all the terminal groups
After producing ~ 40 mol% prepolymer,

Post-polycondensation step: The prepolymer obtained in the above step has a plurality of stirring blades that are continuously bonded to each other. The horizontal length of the plurality of continuous stirring blades is L, and the stirring blades are L. Using a biaxial horizontal reactor having an L / D of 1.5 to 10 where D is the rotational diameter of the polymer, the temperature of the prepolymer is 250 to 350 ° C., and the residence time of the prepolymer is 10 minutes or more. The viscosity average molecular weight is 14,000 to 60,0 by increasing the molecular weight in the range of 5 to 95% of the effective volume of the horizontal reactor.
The present invention provides a method for producing an aromatic polycarbonate resin, which comprises obtaining an aromatic polycarbonate resin having a terminal hydroxyl group concentration of 30 mol% or less based on all terminal groups.

[0008]

SUMMARY OF THE INVENTION Aromatic Dihydroxy Compound As the aromatic dihydroxy compound used as a raw material in the present invention, those represented by the following general formula (I) are used.

[0009]

Embedded image

[In the formula, each of R ¹ and R ² independently represents a hydrogen atom, a halogen, an alkyl group, an alkenyl group or an optionally substituted aryl group, and X is

[0011]

Embedded image (However, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms),

[0012]

Embedded image

Alternatively, it represents --O--, --CO--, --S-- or --SO--. ]

Specific examples of the aromatic dihydroxy compound include bis (4-hydroxyphenyl) methane and 1,1-
Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 2, 2-bis (4
-Hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) pentane, 3,3-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (3
-Methyl-4-hydroxyphenyl) propane, 2,2
-Bis (3-ethyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl-4-hydroxyphenyl) propane, 2,2-bis (3-sec-butyl-4-hydroxyphenyl) propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane,
2,2-bis (4-hydroxyphenyl) hexafluoropropane, bis (4-hydroxyphenyl) phenylmethane, 1,1-bis (4-hydroxyphenyl) -1
-Phenylethane, 1,1-bis (4-hydroxyphenyl) -1-phenylpropane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) dibenzylmethane, 1,1-bis (4-hydroxy) Phenyl) -cyclopentane, 1,1-bis (4-
Hydroxyphenyl) -cyclohexane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone, phenolphthalein and the like can be mentioned. These aromatic dihydroxy compounds may be used alone or as a mixture. Among these, 2,2-bis (4-hydroxyphenyl) propane is preferable.

Carbonic acid diaryl ester The carbonic acid diaryl ester used in the present invention includes:
Bisaryl carbonates or polycarbonate oligomers represented by the following general formula (II) are used.

[0016]

[Chemical 4]

[Wherein, R ^{12 to} R ¹⁵ are each independently a halogen selected from fluorine, chlorine and bromine, a nitro group, an alkyl group having 1 to 6 carbon atoms which may have a substituent, or Indicates an aryl group. Moreover, j represents the integer of 0-20. ]

Examples of the bisaryl carbonates include diphenyl carbonate, bis (p-chlorophenyl) carbonate, bis (o-chlorophenyl) carbonate, bis (2.4-dichlorophenyl) carbonate, bis (p-nitrophenyl) carbonate, Examples of the polycarbonate oligomer include bis (o-nitrophenyl) carbonate and bisphenol A.
Examples thereof include bisallyl carbonate, a polycarbonate oligomer having a phenyl carbonate group at the end, and the like. Particularly preferred is diphenyl carbonate.

In order to produce the aromatic polycarbonate used in the present invention by a transesterification reaction, these carbonic acid diaryl diesters are usually used in order to compensate for the distillation of bisaryl carbonates during polymerization. The amount used is 1 to 1.7 mol, preferably 1.05 to 1.5 mol, per 1 mol of the dihydroxy compound.

[0020] Aromatic polycarbonates endcapping agent present invention, a mono-substituted phenol as a terminal blocking agent may be added as necessary. Examples of monofunctional phenols used for such purposes include cresol, methoxyphenol,
Examples include amylphenol, hexylphenol, octylphenol, cumylphenol and phenylphenol. These monofunctional phenols may be added at the beginning of the polymerization or after the transesterification reaction at the beginning of the polymerization is completed.

In the method for producing an aromatic polycarbonate resin of the present invention, a branched polycarbonate is prepared by adding a trivalent or higher polyfunctional compound such as phloroglucin or 1,1,1-tris (4-hydroxyphenyl) -ethane. It is also possible to Furthermore, terephthalic acid or dicarboxylic acid such as isophthalic acid may be added to obtain an aromatic polyester polycarbonate resin.

Transesterification Catalysts Transesterification catalysts include alkali metal or alkaline earth metal phenolates, carbonates, acetates, phosphates,
Alkali metal compounds or alkaline earth metal compounds such as hydroxides and hydrides, phosphorus compounds such as phenylphosphoric acid, phenylphosphorous acid and metal salts thereof, tetramethylammonium-tetraphenylboranate, tetraphenylphosphonium-tetraphenylboranate Such as ammonium, phosphonium borane salt catalyst, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, trimethylbenzylammonium hydroxide and other ammonium hydroxide, dimethylphenylbenzylammonium chloride, benzyltributylammonium chloride and other quaternary ammonium salts, Triethylamine, 2-methylimidazole, dimethyl-
Examples thereof include amines such as 4-aminopyridine and salts thereof, iminocarboxylic acid derivatives and salts thereof, and the like.

Among these, alkali metal compounds are particularly preferable, and particularly nitrogen-containing alkali metal compounds such as iminocarboxylic acid derivatives such as sodium nitrilotriacetate or salts thereof, and phosphorus-containing alkalis such as disodium phenylphosphate. Preferable examples include metal compounds or alkali metal carbonates such as cesium carbonate and sodium carbonate. These may be used alone or in combination of two or more. The amount of the catalyst is the aromatic dihydroxy compound 1
10 ^-4 to 10 ^-8 mol, preferably 10 ^-5 to mol
It is 10 ^-8 mol, particularly preferably 10 ^-5 to 10 ^-7 mol.

Production Method In the production method of the aromatic polycarbonate resin of the present invention, a prepolymer having a low melt viscosity is produced in the prepolycondensation step, and the prepolymer is polymerized in the postpolycondensation step. (See FIG. 1) i) Pre-polycondensation step: The method for producing the prepolymer is not particularly limited, and it may be produced by a batch method or a continuous method, but a continuous method is preferable. In particular, a method of continuously using a tank type (rigid type) reactor (1) having a stirring rod in the vertical direction is preferable.

The shape of the stirring blade of such a tank type reactor is a Maxblend blade, a full zone blade, a turbine blade,
Paddle wings, anchor wings, helical paddle wings, twisted lattice wings, etc. [Chemical Engineering Handbook, page 911, (revised 5th edition)]. Above all, a tank having a stirring blade provided on the rotating shaft provided in the center of the reaction tank, and a tank having a Maxblend blade in which a part of the stirring blade is formed close to the inner surface of the tank wall formed in a shape along the inner surface of the tank wall Mold reactors are preferred.

The molten product of the aromatic dihydroxy compound and the carbonic acid diaryl ester is supplied from the pipe 2 to the tank reactor. 3 is a pipe for supplying a transesterification catalyst. Reference numeral 4 is a discharge pipe for by-products. The viscosity average molecular weight of the prepolymer obtained in this prepolycondensation step is 3,000 to 2
It is 5,000, preferably 5,000 to 20,000, and particularly preferably 8,000 to 20,000.

The viscosity average molecular weight of the prepolymer is 3,000
When it is lower than 0, the polymerization time in the tank reactor is short, but the burden of polymerization in the horizontal reactor in the post-polymerization step is large, and it takes a long time to increase the molecular weight. Needed and not preferred. Further, if the molecular weight of the prepolymer exceeds 25,000, in a conventional tank reactor, the stirring ability is lowered along with the increase in viscosity due to the increase in the molecular weight, which is not preferable. In order to prevent the melt viscosity from increasing, it is necessary to perform the prepolycondensation step at a high temperature of 300 ° C. or higher, which is disadvantageous in that the polymer is colored.

The terminal hydroxyl group concentration of the prepolymer is 1 to 4
It should be 0 mol%. If this concentration exceeds 40 mol%, the concentration of terminal hydroxyl groups in the final polymer will be high, leading to deterioration in coloration and hydrolysis resistance. If it is less than 1 mol%, the reaction rate becomes slow and the residence time becomes long,
Problems of coloring and gelation occur. A preferred range of the terminal hydroxyl group concentration is 3 to 35 mol%, and a particularly preferred range is 5
~ 30 mol%.

The reaction conditions for producing the prepolymer include:
The temperature is preferably in the range of 140 ° C to 320 ° C. It is preferably in the range of 160 to 220 ° C., after which the temperature is gradually raised to finally 250 to 320 ° C., especially 260 to 300 ° C.
It is preferably in the range of ° C. Moreover, the pressure is from normal pressure to
It is in the range of 0.0001 Torr. Although it can be produced in an ordinary reaction tank, it can be produced stepwise in several stages within the above range in the case of continuous production. In the pre-polycondensation step, the transesterification reaction is carried out until the amount of monophenols distilled out of the reaction system becomes 0.8 to 1.20 mol with respect to 1 mol of the aromatic dihydroxy compound used. It is preferable.

Ii) Post-polycondensation step: In the post-polycondensation step, when the biaxial horizontal reactor is used to further increase the molecular weight, the prepolymer obtained in the first stage is directly biaxially melted. It may be fed to a horizontal reactor, or once pelletized, it may be remelted and fed with an extruder or the like, but it is better to feed it directly in a molten state in terms of thermal efficiency and polymer discoloration prevention. preferable.

In the post-polycondensation step, a biaxial horizontal reactor 5 having stirring blades in which the stirring blades are continuously connected to each other is used. The stirring blades 6 and 6 ′ that are continuously connected to each other are the stirring blades that are used and are connected to each other. That is, the ear shafts 8 and 8'for transmitting the stirring power 7 to the stirring blades and all the stirring blades 6 and 6's connected to the ear shafts are in contact with each other and are continuously connected. Further, the connecting portion is the stirring blade itself 6a, 6'a, or a part of the stirring blade,
Alternatively, scrapers and the like used as 6b and 6'b are preferable, and it is preferable that they are not used only as a reinforcing material. Although the horizontal rotary shaft may be present or absent, a horizontal reactor having no horizontal rotary shaft and having a rotating shaft center by continuously connecting stirring blades to each other is preferable.

On the other hand, in the stirring blades which are discontinuous with each other (Japanese Patent Laid-Open No. 2-153925), the stirring blades are connected only through the horizontal rotary shaft, and the stirring blades are not continuously connected to each other. It can be easily distinguished from stirring blades which are continuous with each other. When these discontinuous stirring blades are used, there is a portion that does not substantially contribute to stirring, for example, there is a rotating shaft that is used only for transmitting power or for mounting the stirring blades, and therefore the portion is not present. The polymer is insufficiently renewed, which causes coloration and causes unnecessary gel generation, which is not preferable. Furthermore, if the residence time is reduced to improve renewability, it becomes difficult to polymerize the polymer, or the terminal hydroxyl group concentration must be increased to increase the reaction rate, resulting in coloring and hydrolysis resistance. Is not preferable because it causes a decrease in

Therefore, the stirring blades are preferably continuous, and particularly preferably those without a horizontal rotating shaft that does not contribute to the reaction. The proportion of the horizontal rotary shaft or the like that does not directly contribute to stirring or the like is preferably less than 20% of the volume of the horizontal reactor, and particularly preferably less than 10%. The shape of the stirring blade is not particularly limited, and examples thereof include a disk type, a convex lens type, a round frame type, a window frame type, a pseudo-triangular type, and a modification thereof. Of these, stirring blades having the shape of frame-shaped hollow blades such as round frames and window frames are preferable because the amount of unnecessary polymer attached is less than that of the stirring blades having a plate shape as a whole.

In particular, two rotating ear shafts 8 and 8'are arranged side by side at both ends in the longitudinal direction inside the cylindrical container 9 installed horizontally, which is disclosed in Japanese Patent Publication No. 3-47130. A plurality of rod-shaped rectangular frames 6a, 6b, 6'a,
6'b is attached to a continuous stirring blade, and the rotating shafts arranged side by side are held so that the tips of the corresponding rod-shaped rectangular frames of one stirring blade pass in proximity to the rotation center of the other stirring blade. A biaxial horizontal reactor 5 having a lattice-type stirring blade is preferred.

In the figure, 10 is a vent pipe and 11 is a molten polymer outlet. Incidentally, in the known screw type stirring blades generally described in the literature, it is difficult to obtain a high molecular weight without long residence time, the terminal hydroxyl group concentration cannot be lowered as described later, and the hydrolysis resistance of the polymer is low. Further, the screw blade is strongly sheared, and its coloring due to its heat generation is remarkable, so that it is not preferable to use.

In the horizontal reactor of the present invention, when the length of the continuous stirring blade in the horizontal direction, that is, the length in the longitudinal direction of the rotating shaft is L and the rotating diameter of the stirring blade is D, L / D is 1. .5
It is -10. The value of L / D depends on the shape of the stirring blade, the optimum reaction time, the required molecular weight distribution, etc., but if L / D is made too large, the blade becomes relatively smaller than the number of stirring blades, and thus the stirring efficiency increases. If the L / D is too small, the size of the stirring blade becomes too large, the piston flow property is deteriorated, and the polymerization reaction becomes too long. Suitably L / D is 2 to 10, more preferably 2.5 to 10.

In the present invention, it is necessary to use a biaxial horizontal reactor, and a plurality of these biaxial horizontal reactors may be used. If the reaction temperature in the post-polycondensation step is too low, the reaction becomes slow, the viscosity of the polymer becomes high, and the stirring efficiency becomes poor, which is not preferable. If the reaction temperature is too high, the decomposition of the polymer is promoted, which causes coloration, which is also undesirable. The preferred post-polycondensation temperature range is 2
60 to 320 ° C., particularly preferably 270 to 31
0 ° C. The pressure is 10 Torr or less, preferably 2 Torr or less.

Generally, the shorter the residence time is, the more the temperature is the same, so that the coloring can be prevented. However, if the residence time is shortened, the polymerization can be terminated unless the temperature is made extremely high. It is not possible to do this, and rather it causes coloring, so it is advisable to select the temperature so that the residence time is 10 minutes or more. Usually the residence time is 10 minutes to 120 minutes, preferably 15 minutes.
Minutes to 90 minutes.

It is preferable to carry out the post-condensation polycondensation so that the residence amount of the polymer in the biaxial horizontal reactor is 5 to 95% of the effective internal volume of the reactor. Here, the effective internal volume is the maximum volume that can be filled with the polymer, excluding the volume of the stirring blade, the volume of the selvage, the horizontal axis, etc. from the volume of the tank. The amount of polymer processed per unit time in one horizontal reactor tends to increase as the amount of polymer retained increases, but if the amount of residence is increased too much, the condensation by-product removal efficiency deteriorates and the polymerization time increases. It takes time, and conversely, the treatable amount decreases, causing coloring and deterioration of physical properties due to heat retention.

As the amount of retained polymer decreases, the removal efficiency of condensation by-products improves, but the efficiency of polymer treatment per horizontal reactor decreases, and the polymer remaining in the reaction tank is regenerated. The absolute amount is insufficient, and coloring and deterioration of physical properties are likely to occur due to modification of the residual polymer. The polymer retention amount that maintains the productivity of polymer production and does not cause coloration or deterioration of physical properties is 5 to 95% of the effective internal volume of the horizontal reactor, preferably 10 to 80%, and particularly preferably 15 to 70%. 20-60% is the most preferable.

[0041] The viscosity-average molecular weight of the aromatic polycarbonate resin obtained by the aromatic polycarbonate resin present invention is 14,000～60,000.
The terminal hydroxyl group concentration is 30 mol% or less in all the terminal groups, and depending on the target molecular weight, it is preferably 25 mol% or less, particularly preferably 20 mol% or less, and 15 mol%
The following are the most preferable. The terminal hydroxyl group concentration of this final polymer is the terminal hydroxyl group concentration or catalyst species of the above-mentioned prepolymer,
It can be adjusted by changing the amount.

The aromatic polycarbonate resin may be a known heat stabilizer such as a phosphorus-based heat stabilizer such as phosphite triester, benzenephosphonic acid and acid phosphate, and an antioxidant such as hindered phenol, if necessary. It is possible to add agents to improve their thermal stability. If necessary, the resin may be modified with another resin, or a filler such as glass fiber or carbon fiber, a flame retardant, a UV absorber, a release agent or a colorant may be added.

The polycarbonate resin produced by the method of the present invention is a high-quality aromatic polycarbonate resin excellent in color tone without any problem due to residual methylene chloride. Therefore, the polycarbonate resin can be widely used as a general engineering plastic material such as a sheet, a lens, an optical component such as a compact disc and an optical disc, a transparent component such as an automobile, and a housing of various devices.

[0044]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. (1) Viscosity average molecular weight (Mv) Intrinsic viscosity [η] (d) of a methylene chloride solution at 20 ° C
1 / g) was measured using an Ubbelohde viscosity tube, and the viscosity average molecular weight was calculated using the following formula.

[0045]

[Equation 1] [η] = 1.23 × 10 ⁻⁴ · (Mv) ^0.83 (2) Measurement of terminal hydroxyl group concentration The amount of terminal hydroxyl group is (Macromol. Chem 88 volumes,
A red complex was formed using titanium tetrachloride as described on page 215 (published in 1965) and quantified from the absorbance of light at 546 nm, and the amount of end groups other than the end of the hydroxyl group was determined by alkali decomposition of the polymer, and then aroma such as phenol. The end derived from the group dihydroxy compound was quantified and calculated using them. (3) Color tone of polymer The color tone of pellets is a color computer (SM color computer manufactured by Suga Test Instruments Co., Ltd., model SM-).
Evaluation was made by the b value measured by the reflection method in 4). The larger the b value is, the higher the yellowness is, and as a sample having a good color tone, the b value is 1.5 or less, preferably the b value is 1.0.
It is the following. (4) Q value The Q value was measured according to JIS K6719.

Example 1 Pre-polycondensation step: 4566 g of bisphenol A (20.0
Mol), 4584 g of diphenyl carbonate (21.4
Mol) and trisodium nitrilotriacetate 0.056 g
(0.0002 mol) was charged into a tank reactor having a 30-liter Maxblend blade, and after nitrogen substitution,
The temperature was gradually raised. Stirring was started after the reaction mixture was dissolved, and the time point was defined as the polymerization start time (tank temperature: 180
° C). After that, the temperature was further raised to 270 ° C, the pressure was gradually reduced, the produced phenol was distilled off to continue the reaction, and finally the inside of the tank was maintained at 1 Torr, and the polymerization was completed in 4 hours for the total polymerization time. After the internal pressure was restored, the strand was extruded into a water tank and cut into pellets. The viscosity average molecular weight of the obtained prepolymer was 14,900.
(Terminal hydroxyl group concentration = 19 mol%). The prepolymer was colorless and transparent, and the color tone was 0.1 in b value.

Post-polycondensation step: As a biaxial horizontal reactor,
A reactor in which the frame-type stirring blades disclosed in Japanese Examined Patent Publication No. 3-47130 are sequentially connected substantially at right angles to each other near the center of one side of each frame, and the stirring blades are mutually continuous (L / D = about 3). , Effective internal volume 20 liters), the pellets of the above prepolymer were supplied to this reactor at a rate of 6 kg / hour, and post-polymerization was carried out at 270 ° C., 0.5 mmHg, and a residence time of 60 minutes. The viscosity average molecular weight of the obtained polymer is 22.0.
It was 00 (concentration of terminal hydroxyl group = 8 mol%). The polymer was colorless and transparent, and the color tone was 0.2 in b value. The Q value was 7.6 × 10 ^-2 cm ³ / S.

Example 2 Pre-polycondensation step: A prepolymer was obtained in the same manner as in Example 1 except that 0.044 g (0.0002 mol) of disodium phenylphosphate was used as a catalyst. The viscosity average molecular weight of the obtained prepolymer was 14,500 (terminal hydroxyl group concentration =
15 mol%). The prepolymer was colorless and transparent, and the color tone was 0.1 in b value.

Post-polycondensation step: Using the above prepolymer,
Post-stage polymerization was carried out in the same manner as in Example 1 except that the reaction temperature was 290 ° C. The viscosity average molecular weight of the obtained polymer is 3
It was 1,700 (5 mol%). The polymer was colorless and transparent, and the color tone was 0.3 in b value. The Q value was 1.6 × 10 ^-2 cm ³ / S.

Example 3 Pre-polycondensation step: 0.0065 g of cesium carbonate as a catalyst
A prepolymer was obtained in the same manner as in Example 1 except that (0.00002 mol) was used. The viscosity average molecular weight of the obtained prepolymer was 15,100 (terminal hydroxyl group concentration = 21 mol%). Also, the prepolymer is colorless and transparent,
The color tone was 0.1 in b value.

Post-polycondensation step: Using the above prepolymer,
Post-stage polymerization was carried out in the same manner as in Example 1 except that the reaction temperature was 290 ° C. The viscosity average molecular weight of the obtained polymer was 22,700 (terminal hydroxyl group concentration = 9 mol%). The polymer was colorless and transparent, and the color tone was 0.3 in b value. The Q value was 7.0 × 10 ^-2 cm ³ / S.

Comparative Example 1 Pre-polycondensation step: 4,498 g of diphenyl carbonate
A prepolymer was obtained in the same manner as in Reference Example 1 except that (21.4 mol) was used. The viscosity average molecular weight of the obtained prepolymer was 14,800 (terminal hydroxyl group concentration = 46 mol%). The prepolymer is colorless and transparent, and the color tone is b
The value was 0.2.

Post-polycondensation step: Using the above prepolymer,
Polymerization was carried out under the same conditions as in Example 1 except that the residence time was 30 minutes. It was visually observed that the obtained polycarbonate had a portion that was not partially dissolved in methylene chloride, but the solution portion had a viscosity average molecular weight of 21,900 (terminal hydroxyl group concentration = 31.
Mol%). The color tone was yellowish, and the b value was 1.0. Also, the Q value is 6.2 × 10 ^-2 cm ³ /
It was S.

Comparative Example 2 Pre-Polycondensation Step: The prepolymer pellets obtained in Example 1 were used. Post-polycondensation step: JP-A-2-1539 as a post-polycondensation device
The biaxial horizontal reactor (L / D = 7.5, effective internal volume 2) in which the shape of the stirring blade shown in Japanese Patent Publication No. 25 is a disk, and the stirring blades are vertically connected to a horizontal rotary shaft and have mutually discontinuous stirring blades.
(0 liter) was used to carry out polymerization under the same conditions as in Example 1.
The viscosity average molecular weight of the obtained polycarbonate is 21,800.
(Terminal hydroxyl group concentration = 10 mol%). The color tone was yellowish, and the b value was 0.8. The Q value was 7.2 × 10 ^-2 cm ³ / S.

Comparative Example 3 Pre-polycondensation step: The prepolymer pellets obtained in Example 2 were used. Post-polycondensation step: Polymerization was carried out under the same conditions as in Example 2 using the post-polycondensation apparatus used in Comparative Example 2 as shown in JP-A-2-153925. It was visually confirmed that the obtained polycarbonate had a part that was not soluble in methylene chloride, but the solution part had a viscosity average molecular weight of 30,700.
Met. The color tone was yellowish and the b value was 1.9. The Q value is 1.2 × 10 ^-2 cm ³ /
It was S.

[0056]

According to the method for producing an aromatic polycarbonate resin according to the present invention, there is no problem due to residual methylene chloride, the color tone is excellent, impurities such as gel are not contained, fluidity,
A high-quality aromatic polycarbonate resin having excellent hydrolysis resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of an apparatus for carrying out the invention of the present invention.

FIG. 2 is a partially cutaway top view showing an example of a horizontal biaxial reaction device.

[Explanation of symbols]

 1 Tank-type stirring reaction tank 2 Raw material supply pipe 3 Catalyst supply pipe 4 By-product discharge pipe 5 Biaxial horizontal reactor 6,6 'Stirring blade 7 Motor 8,8' Short shaft 9 Cylindrical container 10 Vent conduit 11 Polymer intake Exit

Claims (3)

[Claims] 1. A method for producing an aromatic polycarbonate resin by a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diaryl ester, wherein a polycondensation step: a molten mixture of the aromatic dihydroxy compound and the carbonic acid diaryl ester is rigidly stirred. The mixture is fed into the reaction tank and the polycondensation reaction of the mixture is carried out to obtain a viscosity average molecular weight of 3,
000 to 25,000, the terminal hydroxyl group concentration is 1 in all the terminal groups
After producing 40 mol% of the prepolymer, a post-polycondensation step: the prepolymer obtained in the above step has a plurality of stirring blades continuously bonded to each other, and the horizontal direction of the continuous stirring blades. Direction length L, stirring blade rotating diameter D
When using a biaxial horizontal reactor having an L / D of 1.5 to 10, the amount of prepolymer retained at a temperature of 250 to 350 ° C. for a residence time of 10 minutes or more is effective content of the biaxial horizontal reactor. It is characterized by obtaining an aromatic polycarbonate resin having a viscosity average molecular weight of 14,000 to 60,000 and a terminal hydroxyl group concentration of 30 mol% or less in all terminal groups by increasing the molecular weight in the range of 5 to 95% of the product. A method for producing an aromatic polycarbonate resin. 2. A biaxial horizontal reactor in which two rotary ear shafts are arranged side by side at both ends in the longitudinal direction in a horizontally arranged cylindrical container, and a plurality of rotary ear shafts are provided between the rotary ear shafts in the longitudinal direction. A continuous stirring blade is attached to the rod-shaped rectangular frame, and the side-by-side rotating shafts are held so that the tips of the corresponding rod-shaped rectangular frames of one stirring blade pass in proximity to the rotation center of the other stirring blade. The method for producing an aromatic polycarbonate resin according to claim 1, wherein a biaxial horizontal reactor having a lattice-type stirring blade is used. 3. The rigid stirring reaction tank of the first step is provided with a stirring blade on a rotating shaft provided at the center of the reaction tank, and a part of the stirring blade is formed along the inner surface of the tank wall. The method for producing an aromatic polycarbonate resin according to claim 1, wherein the aromatic polycarbonate resin has a Maxblend blade in close proximity to the inner surface of the formed tank wall.