JPH06157739A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To obtain an high-molecular weight aromatic polycarbonate excellent in hue, heat resistance, transparency and resistance to water, useful for molded products, etc., by melt polycondensation of an aromatic dihydroxyl compound with a carbonic diester through addition of a terminal blocking agent under specified conditions. CONSTITUTION:Using two or more reaction vessels in series, melt polycondensation is conducted between (A) an aromatic dihydroxyl compound such as bis(4-hydroxyphenyl)methane and (B) a carbonic diester such as diphenyl carbonate; into at least one of the reaction vessels with the intrinsic viscosity [eta]of the resultant polymer being >=0.20dl/g at the inlet, pref. 0.5-5mol% (per mol of the component A) of a terminal blocking agent such as a 17-50C carbonic diester is added and the melt polycondensation is continued, thus obtaining the objective polycarbonate.

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 an end-capped aromatic polycarbonate, and more particularly to a method for producing an aromatic polycarbonate having a high degree of polymerization at a high polymerization rate.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used because they are excellent in mechanical properties such as impact resistance, heat resistance and transparency. As a method for producing an aromatic polycarbonate, a method in which an aromatic dihydroxy compound such as bisphenol A is directly reacted with phosgene (interfacial method), or an aromatic dihydroxy compound such as bisphenol A and a carbonic acid diester such as diphenyl carbonate are melted A method of transesterification (polycondensation reaction) is known. Although the former method is generally practiced at present, the latter method is considered to be promising in the future because it does not use a troublesome compound such as phosgene.

The latter method generally uses bisphenol A.
(Melting point 156 ° C.) and diphenyl carbonate (melting point 8
(0 ° C.) is melted by heating, a catalyst is added to a mixed solution of both compounds, and then polycondensation is performed while heating to a reaction temperature with a heating medium.

In the polycondensation, an end-capping agent is usually used in order to improve the hue, heat resistance, heat aging resistance or water resistance of the polycarbonate produced. For example, in JP-A-2-175723, an aromatic dihydroxy compound and a carbonic acid diester are melt-polycondensed in the presence of a specific catalyst, and a hydroxyl group end of the obtained polycarbonate is sealed with a specific compound. Is listed.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing an aromatic polycarbonate having a high degree of polymerization at a high polymerization rate.

[0006]

The present invention provides a method for producing an aromatic polycarbonate by melt polycondensation of an aromatic dihydroxy compound and a carbonic acid diester using at least two reactors in series, and a method for producing an aromatic polycarbonate. The method is characterized in that a stopping agent is added to at least one of the reactors whose intrinsic viscosity [η] of the polymer at the reactor inlet is 0.20 dl / g or more.

According to the present invention, in the prepolymerization stage in which the intrinsic viscosity of the polymer is relatively low, the intrinsic viscosity of the polymer is relatively high after the polycondensation is promoted rapidly and sufficiently without adding a sealing agent. The end of the aromatic polycarbonate is sealed by adding a sealing agent only in the post-polymerization stage. Thereby, in the pre-polymerization stage, the polymerization of the polymer is carried out quickly and sufficiently, and in the post-polymerization stage, by imparting the conventional effect by the sealing agent, the hue, the heat resistance,
In addition to the effects of heat aging resistance and water resistance, the degree of polymerization of the aromatic polycarbonate produced can be significantly increased.

In the present invention, the reactor supplied with the endcapping agent has an intrinsic viscosity [η] of the polymer at the inlet of 0.
20 dl / g or more, preferably 0.25 dl / g
Or more, and particularly preferably 0.30 dl / g or more. A reactor having an intrinsic viscosity of less than 0.20 dl / g is not preferable because the polymerization reaction is suppressed by the influence of the terminal blocking agent and the degree of polymerization of the polycarbonate produced cannot be increased. Here, the intrinsic viscosity [η] of the polymer is 20 ° C.
The intrinsic viscosity measured in a methylene chloride solution is shown.

If the intrinsic viscosity of the polymer is within the above range, the end-capping agent may be supplied to a single reactor in a predetermined amount in a batch, or if necessary, to a plurality of reactors. It may be dispersed and supplied. Usually, it is preferably fed only to the final reactor in a lump.

An example of the method for producing a polycarbonate according to the present invention will be described below with reference to FIG.

The stirring tank 1 has a stirring blade attached to a vertical rotating shaft, and an aromatic dihydroxy compound and a carbonic acid diester are continuously supplied thereto through pipes 2 and 3, respectively. Oxygen is substantially absent from the stirring tank atmosphere, and the stirring tank is purged with, for example, nitrogen gas. The catalyst is supplied to the stirring tank through the pipe 4 and mixed with the above reaction raw materials.
It is also possible to provide multiple stirring tanks in series to form a homogeneous solution.

The mixed raw materials are supplied to the prepolymerization tank 9 through the pipe 7 by the pump 6. The pre-polymerization tank is equipped with a stirring blade having a vertical rotation axis. The inside of the tank is kept at a reduced pressure by the venting conduit 8 provided at the upper part. The by-produced phenol and a part of the unreacted monomer sucked through the conduit 8 are rectified, the phenol is discharged out of the system, and the unreacted monomer is returned to the polymerization tank. Also, piping 4
It is also possible to supply a further catalyst through ′.

One or more pre-polymerization tanks 9 can be provided in series, and preferably two to four pre-polymerization tanks 9 are provided. The reaction temperature in the first prepolymerization tank is usually 50 to 270 ° C., preferably 150 to 260.
C., and the pressure can be reduced from normal pressure to 6 mmHg, and the lower limit is preferably 400 to 6 mm.
Hg, particularly preferably in the range of 300 to 6 mmHg can be set.

The reaction temperature in the second and subsequent prepolymerization tanks is usually 180 to 300 ° C., preferably 200 to 280.
C., and the pressure is in the range of 1 to 50 mmHg, preferably 1 to 30 mmHg.

The aromatic polycarbonate having a certain degree of polymerization as described above has, for example, an intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C. of 0.05 to 0.5 dl.
/ G, preferably 0.10 to 0.45 dl / g, and more preferably 0.10 to 0.4 dl / g.

Next, the reaction mixture is mixed with a horizontal stirring polymerization tank 13
Supply to. This horizontal stirring polymerization tank has one or more horizontal rotating shafts, and one type of stirring blades such as a disc type, a wheel type, a paddle type, a rod type and a window frame type is provided on the horizontal rotating shaft or Two
This is a horizontal type high-viscosity liquid processing apparatus in which at least two stages are installed per rotary shaft in combination of two or more kinds, and the reaction solution is scraped or spread by the stirring blade to renew the surface of the reaction solution. The reaction temperature there is usually 240-
320 ° C, preferably in the range of 250-310 ° C,
The pressure is 20 mmHg or less, preferably 10 mmHg
It is the following.

At least one horizontal stirring polymerization tank, preferably one or two, is provided in series. The polymer is supplied to the last horizontal stirring polymerization tank 18 by the gear pump 14 through the pipe 15. The polymer had an intrinsic viscosity [η] of 0.20 dl measured in a methylene chloride solution at 20 ° C.
/ G or more, preferably 0.25 dl / g or more, and particularly preferably 0.30 dl / g or more. A terminal end of the aromatic polycarbonate produced by adding a predetermined amount of the end capping agent is sealed through the pipe 16 in the final horizontal stirring polymerization tank 18. A viscous polymer is taken out from the bottom of the last horizontal stirring polymerization tank 18 by a gear pump 19.
Intrinsic viscosity [η] measured in methylene chloride solution at 20 ℃
Is 0.20 to 1.0 dl / g, preferably 0.25
0.9 dl / g, more preferably 0.30 to 0.8 dl
/ G of polycarbonate is obtained.

The above reactors and reaction conditions are merely examples and are not limiting.

The terminal blocking agent used in the present invention is preferably 0.05 to 15 mol%, more preferably 0.2 to 7 mol%, and particularly preferably 1 mol of the aromatic dihydroxy compound as a raw material. 0.5-5 mol% is added. By adding within the above range, the hydroxyl group end of the aromatic polycarbonate produced is sealed, and an aromatic polycarbonate having sufficiently excellent heat resistance and water resistance can be obtained. If the addition amount of the terminal blocking agent is less than 0.05 mol%, the hydroxyl group terminal cannot be sufficiently blocked, which is not preferable, and if it exceeds 15 mol%, an excess of the terminal blocking agent remains in the polymer. ,
It is not preferable because it lowers the physical properties.

The terminal blocker has a carbon number of 17 to 5
Carbon dioxide diester of 0, carbon dioxide diester of 13 to 16 carbon atoms, epoxy compound of 2 to 50 carbon atoms, monoesters of 5 to 40 carbon atoms and the like are preferable. In addition, the number of carbon atoms is 1 within the range that does not increase the terminal hydroxyl group concentration of the polymer.
Phenols of 0-40, preferably 15-40 can also be used at the same time as the above carbonic acid diesters.

The carbonic acid diester having 17 to 50 carbon atoms is known from JP-A-2-175723 and has the general formula:

[0022]

[Chemical 1] (In the formula, A is a group having 6 to 25 carbon atoms, and B is a group having 1 carbon atom.
A group of 0 to 25, and the sum of the carbon numbers of A and B is 49 or less).

As the above carbonic acid diester, for example, a compound represented by the following formula is used.

[0024]

[Chemical 2] (In the formula, R ¹ is a hydrocarbon group having 3 to 36 carbon atoms)

[0025]

[Chemical 3] (In the formula, R ² and R ³ may be the same or different, R ² is a hydrocarbon group having 1 to 19 carbon atoms, and R ³ is a hydrocarbon group having ³ to 19 carbon atoms. Is a hydrogen radical,
The sum of carbon numbers of R ² and R ³ is 37 or less. )

[0026]

[Chemical 4] (In the formula, R ⁴ is a hydrocarbon group having 1 to 30 carbon atoms, and R ^4
5 is a hydrocarbon group having 1 to 20 carbon atoms, and the sum of carbon numbers of R ⁴ and R ⁵ is 3 or more and 36 or less. )

[0027]

[Chemical 5] (In the formula, R ⁶ is a hydrocarbon group having 4 to 37 carbon atoms.)

[0028]

[Chemical 6] (In the formula, R ⁷ and R ⁸ may be the same or different, R ⁷ is a hydrocarbon group having 1 to 30 carbon atoms, and R ⁸ is a hydrocarbon group having 2 to 20 carbon atoms. Is a hydrogen radical,
The sum of carbon numbers of R ⁷ and R ⁸ is 36 or less. ) Examples of such carbonic acid diesters include carbobutoxyphenylphenyl carbonate, methylphenylbutylphenyl carbonate, ethylphenylbutylphenyl carbonate, dibutyldiphenylcarbonate, biphenylphenylcarbonate, dibiphenylcarbonate, cumylphenylphenylcarbonate, dicumylphenylcarbonate, Naphthyl phenyl phenyl carbonate, dinaphthyl phenyl carbonate, carbopropoxy phenyl phenyl carbonate, carbo heptoxy phenyl phenyl carbonate, carbo methoxy t
-Butylphenylphenyl carbonate, carbopropoxyphenylmethylphenylphenyl carbonate, chromanylphenyl carbonate, dichromanyl carbonate and the like are preferably used.

The carbonic acid diester having 13 to 16 carbon atoms is also known from the above publication. For example, diphenyl carbonate, triphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, phenyltolyl carbonate and the like can be mentioned.

As the epoxy compound having 2 to 50 carbon atoms, those described in JP-A-4-175368 can be used. For example, epoxidized soybean oil, epoxidized linseed oil, phenylglycidyl ether, allylglycidyl ether, t-butylphenylglycidyl ether, 3,4-epoxycyclohexylmethyl 3,4-
Epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
2,3-Epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 4- (3,4-epoxy-5-methylcyclohexyl) butyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylethylene oxide, cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6-methylcyclohexanecarboxylate, bisphenol-A diglycidyl ether, tetrabromobisphenol-A glycidyl ether, diglycidyl ester of phthalic acid, Hexahydrophthalic acid diglycidyl ester, bis-epoxydicyclopentadienyl ether, bis-epoxyethylene glycol, bis-epoxycyclohexyl ester Ruajipeto, butadiene diepoxide, tetraphenyl ethylene epoxide, octyl epoxy tallate, epoxidized polybutadiene, 3,4
Dimethyl-1,2-epoxycyclohexane, 3,5-
Dimethyl-1,2-epoxycyclohexane, 3-methyl-5-t-butyl-1,2-epoxycyclohexane, octadecyl-2,2-dimethyl-3,4-epoxycyclohexanecarboxylate, N-butyl-2
2-dimethyl-3,4-epoxycyclohexanecarboxylate, cyclohexyl-2-methyl-3,4-epoxycyclohexanecarboxylate, N-butyl-
2-isopropyl-3,4-epoxy-5-methylcyclohexanecarboxylate, octadecyl-3,4-
Epoxycyclohexanecarboxylate, 2-ethylhexyl-3 ', 4'-epoxycyclohexanecarboxylate, 4,6-dimethyl-2,3-epoxycyclohexyl-3', 4'-epoxycyclohexanecarboxylate, 4,5-epoxy anhydrous Tetrahydrophthalic acid, 3-t-butyl-4,5-epoxy tetrahydrophthalic anhydride, diethyl 4,5-epoxy-cis-1,
2-cyclohexanedicarboxylate, di-n-butyl-3-t-butyl-4,5-epoxy-cis-1,2
-Cyclohexanedicarboxylate and the like.

Examples of the monoesters having 5 to 40 carbon atoms include undecanoic acid, lauric acid, tridecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, heneicosanoic acid, tricosanoic acid. Examples thereof include alkyl monocarboxylic acids such as acid and melicic acid, and methyl monocarboxylic acid esters such as methyl ester, ethyl ester and phenyl ester of the above alkyl monocarboxylic acids such as methyl stearate, ethyl stearate and phenyl stearate.

Further, as phenols which can be used at the same time as the above-mentioned carbonic acid diester, there is disclosed in JP-A 2-1.
No. 75723, known from, for example, on-butylphenol, mn-butylphenol, pn-butylphenol, o-isobutylphenol, m-isobutylphenol, p-isobutylphenol, ot-butylphenol, mt -Butylphenol, pt-
Butylphenol, on-pentylphenol, m-
n-pentylphenol, pn-pentylphenol, on-hexylphenol, mn-hexylphenol, pn-hexylphenol, o-cyclohexylphenol, m-cyclohexylphenol, p
-Cyclohexylphenol, o-phenylphenol, m-phenylphenol, p-phenylphenol, on-nonylphenol, mn-nonylphenol, pn-nonylphenol, o-cumylphenol, m-cumylphenol, p -Cumylphenol, o
-Naphthylphenol, m-naphthylphenol, p-
Naphthylphenol, 2,6-di-t-butylphenol, 2,5-di-t-butylphenol, 2,4-di-
t-butylphenol, 3,5-di-t-butylphenol, 2,5-dicumylphenol, 3,5-dicumylphenol,

[0033]

[Chemical 7] Coumarone derivatives, for example

[0034]

[Chemical 8] And other monohydric phenols. Among such phenols, binuclear phenols having two aromatic nuclei are preferable, and p-cumylphenol and p-phenylphenol are particularly preferable.

The above-mentioned phenols are used in an amount of less than 1 mol based on 1 mol of carbonic acid diester as an end-capping agent. When the amount used is more than 1 mol, the terminal hydroxyl group concentration of the polymer becomes high, which is not preferable.

In the present invention, the polymer means a polycondensation product of an aromatic dihydroxy compound and a carbonic acid diester.

Here, the aromatic dihydroxy compound has the following formula [I]:

[0038]

[Chemical 9] (Where X is

[0039]

[Chemical 10] -O-, -S-, -SO- or -SO _2- , R
⁹ and R ¹⁰ are hydrogen atoms or monovalent hydrocarbon groups,
R ¹¹ is a divalent hydrocarbon group. Further, the aromatic nucleus may have a monovalent hydrocarbon group. ) Is a compound represented by.

As such an aromatic dihydroxy compound,
For example, bis (4-hydroxyphenyl) methane, 1,1
-Bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-3-t-butylphenyl) Propane, bis (hydroxyaryl) alkanes such as 2,2-bis (4-hydroxy-3-bromophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4- Bis (hydroxyaryl) cycloalkanes such as hydroxyphenyl) cyclohexane, dihydroxyaryl ethers such as 4,4′-dihydroxydiphenyl ether and 4,4′-dihydroxy-3,3′-dimethylphenyl ether,
4,4'-dihydroxydiphenyl sulfide, 4,4
Dihydroxydiaryl sulfides such as ′ -dihydroxy-3,3′-dimethyldiphenyl sulfide,
4,4'-dihydroxydiphenyl sulfoxide, 4,
Dihydroxy diaryl sulfoxides such as 4'-dihydroxy-3,3'-dimethylphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfone, 4,
Examples thereof include dihydroxydiarylsulfones such as 4′-dihydroxy-3,3′-dimethyldiphenylsulfone, and 2,2-bis (4-hydroxyphenyl) propane (so-called bisphenol A) is particularly preferable.

The carbonic acid diester is, for example, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate or the like. And diphenyl carbonate is particularly preferable.

The carbonic acid diester as described above may contain dicarboxylic acid or dicarboxylic acid ester in an amount of preferably 50 mol% or less, more preferably 30 mol% or less. Examples of the dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When a dicarboxylic acid or a dicarboxylic acid ester is used in combination with a carbonic acid diester, a polyester polycarbonate is obtained.

The melt polycondensation rate of the aromatic dihydroxy compound and the carbonic acid diester is influenced by, for example, the amount of the catalyst to be added, the polycondensation temperature, the degree of vacuum, the degree of polymerization and the concentration of the terminal hydroxyl group of the polymer. The effect of the concentration of terminal hydroxyl groups on the polymer is such that the polycondensation rate becomes maximum when the concentration is 50%, and the polycondensation rate decreases when the concentration is higher or lower than 50%. In the pre-polymerization stage,
To achieve a higher polycondensation rate, the terminal hydroxyl group concentration is preferably 30 to 70%, more preferably 35 to 65%,
Especially preferably, it is 40 to 60%. If the concentration of the terminal hydroxyl groups exceeds 70% or less than 30%, the polycondensation rate of the aromatic dihydroxy compound and the carbonic acid diester is slow and the degree of polymerization of the aromatic polycarbonate produced cannot be increased, which is not preferable. The terminal hydroxyl concentration as described above is
The carbonic acid diester is preferably 0.95 to 1.05 mol, more preferably 0.97 to 1.03 mol, and particularly preferably 0.98, based on 1 mol of the aromatic dihydroxy compound.
It can be achieved by using an amount of ˜1.02 mol.

Here, the terminal hydroxyl group of the polymer is a terminal hydroxyl group based on the aromatic dihydroxy compound in the polymer. The terminal hydroxyl group concentration is the ratio of the terminal hydroxyl groups based on the aromatic dihydroxy compound to all the terminal groups in the polymer, and is an index showing the degree of terminal blocking of the polymer. For example, a terminal hydroxyl group concentration of 0% means a state in which all terminal hydroxyl groups based on an aromatic dihydroxy compound are replaced with groups based on another compound. The terminal hydroxyl group concentration can be measured using ¹³ C-NMR.

A compound having three or more functional groups (preferably a phenolic hydroxyl group or a carboxyl group) in one molecule can be further added, and preferably 0.001 to 0.03 mol per 1 mol of the aromatic dihydroxy compound. , Especially in an amount of 0.001 to 0.01 mol. Examples of such compounds are described in JP-A-4-89824.

The polymerization reaction proceeds in the presence of a catalyst. As the catalyst, any known catalyst can be used.
For example, a catalyst system comprising (a) a nitrogen-containing basic compound and (b) an alkali metal compound or an alkaline earth metal compound described in JP-A-2-124934, or (c) boric acid or boric acid. A catalyst system consisting of esters can be used. It is also possible to use a catalyst system composed of an electron-donating amine compound and potassium borohydride or an alkali metal compound or an alkaline earth metal compound described in JP-A-4-46927 and 4-46928. Also, JP-A-60-51719
A catalyst system composed of a nitrogen-containing basic compound and a boron compound described in the publication can be used.

As the reactor used in the present invention, any known reactor may be used, and it may be a continuous type, a semi-continuous type or a batch type, but a continuous type is preferable. In general, a reactor having a different stirring mode is used in the pre-polymerization stage where the viscosity of the reaction system is low and the post-polymerization stage where the viscosity is high. Examples of the reactor include a vertical stirring polymerization tank, a horizontal stirring polymerization tank, and a reaction type extruder.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0049]

EXAMPLES The physical properties of the polycarbonates produced in the examples and comparative examples were measured as follows.

Terminal hydroxyl group concentration: 0.4 g of the sample was dissolved in 3 ml of chloroform and ¹³ C was added at 40 ° C.
-Terminal hydroxyl groups and terminal blocking groups were quantified using -NMR (manufactured by JEOL Ltd., GX-270), and the terminal hydroxyl group concentration was calculated by the following formula.

Terminal hydroxyl group concentration (%) = (number of terminal hydroxyl groups /
Total number of end groups) × 100 Intrinsic viscosity [η]: Measured in methylene chloride at 20 ° C. using an Ubbelohde viscometer.

Hue (b value): X, Y, and Z values of a 3 mm thick injection plate are calculated by Color an of Nippon Denshoku Industries Co., Ltd.
d Color Difference Meter
ND-1001D was used and measured by the transmission method, and the YI value was used as a measure of yellowness.

YI = (100 / Y) × (1.277X−
1.060Z) Thermal aging resistance: A 3 mm thick injection-molded plate was kept in an oven at 120 ° C. for 10 days, and then the YI of this test piece was measured.

[0054]

Example 1 The polymerization reactor shown in FIG. 1 was used. There are two pre-polymerization tanks and two horizontal stirring polymerization tanks. The respective reaction conditions are as follows.

Pressure (torr) Temperature (° C.) Average residence time (hr) Stirring tank Nitrogen atmosphere 130 2.0 Prepolymerization tank A 100 210 1.0 1.0 Prepolymerization tank B 20 240 0.5 Horizontal stirring polymerization tank A 3 285 0.5 Horizontal stirring polymerization tank B 0.3 290 0.5 Bisphenol A (Japan GE Plastics Co., Ltd.)
0.4400 kmol, diphenyl carbonate (manufactured by Any Co.) 0.4444 kmol, and tetramethylammonium hydroxide as a catalyst 0.11 mol (2.5 × 10 ⁻⁴ mol / mol-bisphenol A), water 0.00044 mol (1 × 10 ⁻⁶ mol / mol-bisphenol A) of sodium oxide was continuously supplied to the stirring tank maintained at the above temperature to prepare a uniform solution.

Then, the solution is treated with prepolymerization tank A and prepolymerization tank B.
Then, the mixture was sequentially supplied to the horizontal stirring polymerization tank A to proceed polycondensation.
The intrinsic viscosity of the polymer taken out from the horizontal stirring polymerization tank A was 0.38 dl / g. The polymer was supplied to a horizontal stirring polymerization tank B. Further, in the horizontal stirring polymerization tank B, p-cumylphenylphenyl carbonate was used as a terminal blocking agent in an amount of 1.
5 mol% was added. In the horizontal stirring polymerization tank B, polymerization was carried out under the above reaction conditions to produce a polycarbonate.

The terminal hydroxyl group concentration of the obtained polycarbonate was 4%, and the intrinsic viscosity was 0.55 dl / g.

The hue was 1.4 and the hue after heat aging was 4.6.

[0059]

Example 2 Bisphenol A using p-cumylphenylphenyl carbonate as a terminal blocking agent in each of horizontal stirring polymerization tank A and horizontal stirring polymerization tank B
0.5 mol% and 1.0 mol% respectively were added. The intrinsic viscosity of the polymer at the inlets of the horizontal stirring polymerization tank A and the horizontal stirring polymerization tank B is 0.21 dl / g, respectively.
And 0.35 dl / g. A polycarbonate was produced in the same manner as in Example 1 except for the above.

The terminal hydroxyl group concentration of the obtained polycarbonate was 2%, and the intrinsic viscosity was 0.53 dl / g.

The hue was 1.3 and the hue after heat aging was 4.5.

[0062]

Example 3 Example 3 was repeated except that the p-cumylphenyl carbonate used in Example 1 was replaced by di-p-cumylphenyl carbonate in an amount of 1.5 mol% based on bisphenol A used as a raw material. A polycarbonate was produced in the same manner as in Example 1.

The terminal hydroxyl group concentration of the obtained polycarbonate was 2%, and the intrinsic viscosity was 0.54 dl / g.

The hue was 1.4 and the hue after heat aging was 4.7.

[0065]

Example 4 The same as Example 1 except that diphenyl carbonate was added in place of p-cumylphenylphenyl carbonate used in Example 1 in an amount of 1.5 mol% based on bisphenol A used as a raw material. A polycarbonate was produced.

The terminal hydroxyl group concentration of the obtained polycarbonate was 5%, and the intrinsic viscosity was 0.55 dl / g.

The hue was 1.3 and the hue after heat aging was 4.4.

[0068]

Comparative Example 1 Polycarbonate was produced by carrying out polycondensation in the same manner as in Example 1 except that p-cumylphenylphenyl carbonate was not added.

The polycarbonate obtained had a terminal hydroxyl group concentration of 40% and an intrinsic viscosity of 0.57 dl / g.

The hue was 1.6 and the hue after heat aging was 12.6.

[0071]

Comparative Example 2 Example 1 except that the total amount of p-cumylphenyl phenyl carbonate was added in the prepolymerization tank A.
Polycondensation was carried out in the same manner as above to produce a polycarbonate. Here, the intrinsic viscosity of the polymer at the inlet of the prepolymerization tank A was 0.02 dl / g.

The terminal hydroxyl group concentration of the obtained polycarbonate was 1%, and the intrinsic viscosity was 0.36 dl / g.

The hue was 1.4 and the hue after heat aging was 4.3.

[0074]

Comparative Example 3 Polycarbonate was produced by carrying out polycondensation in the same manner as in Comparative Example 2 except that di-p-cumylphenyl carbonate was used instead of p-cumylphenylphenyl carbonate used in Comparative Example 2. .

The polycarbonate obtained had a terminal hydroxyl group concentration of 1% and an intrinsic viscosity of 0.34 dl / g.

The hue was 1.5 and the hue after heat aging was 4.5.

[0077]

Comparative Example 4 Polycarbonate was produced by carrying out polycondensation in the same manner as in Comparative Example 2 except that diphenyl carbonate was used instead of p-cumylphenyl phenyl carbonate used in Comparative Example 2.

The terminal hydroxyl group concentration of the obtained polycarbonate was 1%, and the intrinsic viscosity was 0.37 dl / g.

The hue was 1.4 and the hue after heat aging was 4.6.

As described above, the aromatic polycarbonate obtained by the method of the present invention had a remarkably high intrinsic viscosity and an excellent degree of polymerization as compared with those of the comparative examples.

[0081]

According to the method of the present invention, an aromatic polycarbonate having a remarkably excellent degree of polymerization can be produced.

[Brief description of drawings]

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

[Explanation of symbols]

 1. Stirring tank 2, 3, 7, 11, 15, 20. Piping 4,4 '. Catalyst inlet 6,10,14,19. Pumps 8, 12, 17. Vent conduit 9. Pre-polymerization tank 13,18. Horizontal stirring polymerization tank 16. Terminal sealant inlet m ≧ 1, n ≧ 0

Claims (2)

[Claims] 1. A method for producing an aromatic polycarbonate by melt polycondensation of an aromatic dihydroxy compound and a carbonic acid diester using at least two reactors in series, wherein an end-capping agent is added at the reactor inlet. A method comprising adding to a reactor having an intrinsic viscosity [η] of 0.20 dl / g or more. 2. The method according to claim 1, wherein the reactor to which the end-capping agent is added is only the final reactor.