JPH02153925A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To obtain the title high-molecular weight polymer having improved strength and color tone by polymerizing an aromatic organic dihydroxyl group compound with a carbonic acid diester by a tank type reaction tank having an agitating element attached to a vertical revolving shaft and a horizontal stirring polymerization tank having an agitating element attached to a horizontal revolving shaft. CONSTITUTION:An aromatic organic dihydroxyl group compound and a carbonic acid diester in a molten state are fed to one or more tank type reaction tanks 1, 7 and 10 having an agitating element attached to a vertical revolving shaft, subjected to polycondensation to form a polymer having 0.05-0.4dl/g intrinsic viscosity [eta] (measured in CH2Cl2 at 20 deg.C). The polymer is fed to a horizontal stirring polymerization tank 20 having mutually discontinuous agitating elements with length L and diameter D perpendicularly attached to a horizontal revolving shaft and 1-15 L/D and subjected to polycondensation to give the aimed polymer having 0.3-1.0dl/g [eta].

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for producing polycarbonate, and more particularly to a method for producing polycarbonate by a transesterification reaction between an aromatic organic trihydroxy compound and a carbonic acid diester.

Technical background of the invention and its problems Polycarbonate is widely used because it has excellent mechanical properties such as impact resistance, as well as excellent heat resistance and transparency. One of the methods for producing such polycarbonate is a method in which an aromatic organic trihydroxy compound such as bisphenol and a carbonic acid diester such as diphenyl carbonate are subjected to a transesterification reaction (polycondensation reaction) in a molten state. For example, Belgian Patent No. 532,543 (1954) describes that bisphenol A and diphenyl carbonate are transesterified in a molten state in the presence of a small amount of transesterification catalyst, and the by-produced phenol is eliminated to form polycarbonate. A method for obtaining the is disclosed. The transesterification reaction carried out in the molten state is generally a bulk polymerization reaction, and the by-product phenol is heated under stirring and mixing at a reaction temperature of 150°C to about 350°C, which is the minimum temperature required to start the transesterification reaction. Gradually increase the pressure from atmospheric pressure to about 0. It is distilled off from the reaction mixture by gradually lowering the reaction pressure to lmmHg.

However, as the above reaction approaches completion,
Because the viscosity of the reaction mixture becomes extremely high (approximately io, ooo to 100,000 voids or more, depending on the reaction conditions), it is difficult to efficiently distill off distillates such as by-product phenol from the reaction mixture. There was a problem that.

To solve this problem, transesterification has conventionally involved a pre-polycondensation step in which a low molecular weight prepolymer is synthesized under normal stirring conditions, while the viscosity of the reaction mixture is relatively low. The process is divided into a post-polycondensation stage in which a high molecular weight polymer is synthesized using a special stirring type in a raised state. The transesterification reaction in the pre-polycondensation step to synthesize low molecular weight prepolymers is
Generally, a seed reactor is used and the reaction is carried out either batchwise or continuously. In addition, the transesterification reaction in the post-polycondensation step of synthesizing high molecular weight polymers can be carried out using a batch method using a seed reactor with a stirring device with a special shape of stirring blades, a centrifugal thin film evaporator, a vented extruder, etc. It is carried out using a continuous method.

However, none of the above methods has been able to achieve the effect of satisfactorily and efficiently distilling by-product distillates such as phenol from the reaction mixture.

By the way, when a tank reactor is used as a polycondensation reactor in the final stage of the transesterification reaction, it is not possible to increase the evaporation surface area per unit treatment of the reaction mixture. It is necessary to increase the residence time. Therefore, since the reaction mixture undergoes a long thermal history, there is a problem that the resulting product has a high degree of coloration.

In addition, when a centrifugal thin film evaporator is used as the polycondensation reactor in the final stage of the transesterification reaction, the evaporation surface area per unit treatment of the reaction mixture can be increased, so centrifugal thin film evaporation of the reaction mixture is possible. Residence time in the machine can be shortened. However, a part of the produced polymer adheres to the rotating shaft, blades, internal bearings, etc. and undergoes a long thermal history, so there is a problem that blackened decomposition products are mixed into the polymer.

In addition, when a single-screw vented extruder is used as a polycondensation reactor in the final stage of the transesterification reaction, some of the produced polymer adheres to the screw groove.
The problem is that undesirably colored products are obtained.

In addition, when using a self-cleaning type twin-screw, vented extruder as the polycondensation reactor in the final stage of the transesterification reaction, colored products are produced because the polymer rarely adheres to a part of the screw. Never. However, this twin-screw vent type extruder has a small hold-up due to its device structure, and the device cost per unit effective volume is extremely high, so there is a limit to scaling up. Therefore, it is necessary to shorten the residence time of the reaction mixture as much as possible, and the reaction temperature and degree of vacuum must be set to stricter conditions than in the pre-polycondensation reaction stage, so that the produced polymer is particularly affected by the reaction temperature. There are problems with coloring and deterioration.

OBJECT OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above, and aims to provide a polycarbonate that has excellent mechanical properties and improved color tone. The purpose is to provide a method for producing polycarbonate.

Summary of the Invention The method for producing polycarbonate according to the present invention is to produce polycarbonate by melt polycondensation of an aromatic organic trihydroxy compound and a diester carbonate. A polycondensation reaction is carried out by supplying the polycondensation reaction to at least one tank-type reaction tank equipped with a stirring blade attached to a vertical rotating shaft, and the intrinsic viscosity [n1] is determined in a methylene chloride solution at 20°C.
η] is 0.05 to 0.4dj! /g of the polycarbonate obtained in the first polycondensation step,
It has a horizontal rotation axis and mutually discontinuous stirring blades attached almost at right angles to the horizontal rotation axis, and when the length of the horizontal rotation axis is L and the rotation diameter of the stirring blade is D, L/
The polycondensation reaction is carried out by supplying to at least one horizontal stirring polymerization tank in which D is 1 to 15, and the above-mentioned intrinsic viscosity [η]
and a second polycondensation reaction step to obtain a polycarbonate having a polycarbonate of 0.3 to 1.0 dl/r.

According to the present invention, a high molecular weight polycarbonate having excellent mechanical properties and improved color tone can be produced.

DETAILED DESCRIPTION OF THE INVENTION The method for producing polycarbonate according to the present invention will be specifically described below.

In the present invention, when producing polycarbonate, an aromatic organic trihydroxyl group compound and a carbonic acid diester are used.

The aromatic organic trihydroxy compound used in the present invention is:
The following formula [1] is -5o- or -5O2-, R1 and R2 are hydrogen atoms or monovalent hydrocarbon groups, and R3 is a divalent hydrocarbon group. Moreover, the aromatic nucleus may have a monovalent hydrocarbon group. ).

Specifically, such aromatic organic trihydroxy compounds include 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-■-methylphenyl)propane, 1.1-bis(4-hydroxy-1-butylphenyl)propane ,
2,2-bis(4-hydroxy-3-bromophenyl)
Bis(hydroxyaryl)alkanes such as propane, bis(hydroxyaryl)cycloalkanes such as 1.1-bis(4-hydroxyphenyl)cyclopentane, 1.1-bis(4-hydroxyphenyl)cyclohexane, 4, 4°-dihydroxydiphenyl ether,
4. Dihydroxyaryl ethers such as 4'-dihydroxy-3,3°-dimethylphenyl ether, 4,
4°-dihydroxydiphenyl sulfide, 4,4°-
Dihydroxydiaryl sulfides such as dihydroxy-3,:It'-dimethyldiphenyl sulfide, 4
．． 4-dihydroxydiphenyl sulfoxide, 4,4-
Dihydroxydiaryl sulfoxides such as dihydroxy-3,3°-dimethyldiphenyl sulfoxide, 4
．． 4'-dihydroxydiphenylsulfone, 4,4゛-
Dihydroxydiarylsulfones such as dihydroxy-3,3-dimethyldiphenylsulfone are used.

Among these, 2,2-bis(4-hydroxyphenyl)propane is particularly preferred.

Further, as the carbonic acid diester, specifically, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, -cresyl carbonate, dinaphthyl carbonate, bis(diphenyl) carbonate, etc. are used.

Among these, diphenyl carbonate is particularly preferred.

Further, these carbonic acid diesters may contain dicarboxylic acid or dicarboxylic acid ester. Examples of such dicarboxylic acids or dicarboxylic acid esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate.

When a dicarboxylic acid or a dicarboxylic acid ester as described above is used in combination with a diester carbonate, a polyester polycarbonate is obtained, and the method for producing a polycarbonate of the present invention also includes a method for producing this polyester polycarbonate.

When producing polycarbonate in the present invention, the carbonic acid diester as described above is used in an amount of 1.01 to 1.30 mol, preferably 1.01 to 1.30 mol, per 1 mol of the aromatic organic trihydroxy compound.
．． It is used in an amount of 0.02 to 1.20 mol.

In the present invention, when polycarbonate is produced by melt polycondensation of the above aromatic organic trihydroxy compound and diphenyl carbonates, a terminal capping agent having a carbon number of 17 to 50, preferably 17 to 50 carbon atoms is added to the reaction system. 40 carbonic acid diester to the aromatic organic trihydroxy compound.
It can also be produced in an amount of 0.5 to 10 mol %, preferably 0.5 to 7 mol %, more preferably 1 to 5 mol %.

As a carbonic acid diester having 17 to 50 carbon atoms as an end-blocking agent, it is usually - formula % formula % (wherein A is a group having 6 to 25 carbon atoms, and B is a group having 1 carbon number).
It is a group of 0 to 25. ) is used.

Specifically, the following compounds are used as the above-mentioned carbonic acid diesters.

(In the formula, R1 is a hydrocarbon group having 3 to 18 carbon atoms.) (In the formula, R2 and R8 may be the same or different, and R2 is a hydrocarbon group having 1 to 19 carbon atoms. R3 is a hydrocarbon group having 4 to 19 carbon atoms) (In the formula, R4 is a hydrocarbon group having 1 to 17 carbon atoms, and R5 is a hydrocarbon group having 1 to 11 carbon atoms) (In the formula , R6 is a hydrocarbon group having 4 to 19 carbon atoms) (wherein, R and R8 may be the same,
They may also be different, and R7 has 1 to 19 carbon atoms,
(R8 is a hydrocarbon group having 3 to 18 carbon atoms) More specifically, the following compounds are preferably used as the carbonic acid diester as the terminal capping agent used in the present invention as described above.

Carbobutoxyphenylphenyl carbonate, methylphenylbutylphenyl carbonate, ethylphenylbutylphenyl carbonate, dibutyldiphenyl carbonate, biphenylphenyl carbonate, diphenyl carbonates mylphenylphenyl carbonate,
dicumylphenyl carbonate, naphthylphenyl phenyl carbonate, dinaphthylphenyl carbonate,
These include carbopropoxyphenylphenyl carbonate, carbohebutoxyphenylphenyl carbonate, carbomethoxy t-butylphenylphenyl carbonate, carboprotoxyphenylmethylphenylphenyl carbonate.

When such diester carbonate is used as an end-capping agent, the entire amount may be added to the reaction system in advance, or a portion may be added to the reaction system in advance, and the remainder may be added as the reaction progresses. You can. Furthermore, in some cases, the entire amount may be added to the reaction system after the polycondensation reaction between the aromatic organic trihydroxy compound and the carbonic acid diester has partially proceeded.

In the present invention, as a terminal capping agent, alkylphenols having 10 to 40 carbon atoms, preferably 15 to 40 carbon atoms are added to the reaction system in a proportion of 0.05 to 0.05 to
It is also possible to prepare polycarbonates present in amounts of 10 mol%, preferably 0.5 to 7 mol%, more preferably 1 to 5 mol%.

In the present invention, the following compounds are used as alkylphenols having 10 to 40 carbon atoms.

on-butylphenol 1-n-butylphenol p-n-butylphenol 0-isobutylphenol - Isobutylphenol p-isobutylphenol o-t-butylphenol 5-t-butylphenol pt-butylphenol on-pentylphenol -n-pentylphenol p-n-pentylphenol on-hexylphenol -n-hexylphenol p-n-hexylphenol 0-Cyclohexylphenol --Cyclohexylphenol p-cyclohexylphenol 0-phenylphenol monophenylphenol p-phenylphenol on-nonylphenol --〇nonylphenol p-n-nonylphenol 0-cumylphenol Haze-cumylphenol p-cumylphenol 0-Naphthylphenol m-naphthylphenol p-naphthylphenol 2,8-di-t-butylphenol 2,5-di-t-butylphenol 2,4-di-t-butylphenol 3,5-di-t-butylphenol 2,5-dicumylphenol 3,5-dicumylphenol It is a monohydric phenol with the following structure.

Among such alkylphenols, dinuclear phenols having two aromatic nuclei are preferred, and p-cumylphenol, p-phenylphenol, and the like are particularly preferred.

When using such alkylphenols as end-capping agents, the entire amount may be added to the reaction system in advance, or a portion may be added to the reaction system in advance and the remainder added as the reaction progresses. You may. Furthermore, in some cases, the entire amount may be added to the reaction system after the polycondensation reaction between the aromatic organic trihydroxy compound and the carbonic acid diester has partially proceeded.

In the present invention, a conventionally known catalyst or a catalyst newly developed by the applicant may be used to produce polycarbonate by melt polycondensation of the above-mentioned aromatic organic trihydroxy compound and carbonic acid diester. Can be done. For example, catalysts described in Japanese Patent Publication No. 8B-894 or No. 3B-13942 include alkali metals such as lithium, sodium, and potassium, alkaline earth metals such as magnesium, calcium, and barium, Acetates of metals such as zinc, cadmium, tin, antimony, lead, manganese, cobalt, nickel,
Carbonates, borates, oxides, hydroxides, hydrides, alcolades, etc. are used, and nitrogen-containing basic compounds, boric acid or boric acid esters, phosphorus compounds, etc. are used. Furthermore, other titanates, benzenesulfonates, and the like can also be used.

These catalysts are preferably used in an amount of 10-6 to 10-1 mol, preferably 10-5 to 10-2 mol, per 1 mol of the aromatic organic trihydroxy compound used as a raw material.

Particularly preferred catalyst systems are detailed below.

In the present invention, when manufacturing a polycarbonate by melt polycondensing an aromatic organic dihydroxy compound and a carbonic acid diester, (a) a nitrogen-containing basic compound (b) an alkali metal compound or an alkaline earth metal compound (C) (a) and (b), (a) and (e), (b) and (e) of boric acid or boric acid ester
It is particularly preferred to use a catalyst consisting of (a), (b) and (c).

(a) As the nitrogen-containing basic compound, specifically, tetramethylammonium hydroxide (M e 4 N
OH), tetraethylammonium hydroxide (Et 4NOH), tetrabutylammonium hydroxide (B u 4 N OH), trime-thylbenzylammonium hydroxide (@tocu (M
e) tetraalkyl or aryl such as 3NOH);
Ararylammonium hydroxides, tertiary amines such as trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine, R2NH (
Secondary amines represented by RNH2 (wherein R is an alkyl group such as methyl or ethyl, or an aryl group such as phenyl or tolyl); Or ammonia, tetramethylammonium borohydride (Me N B H4
), tetrabutylammonylamborohydride (B
u N B H4), tetrabutylammonium tetraphenylborate (B u N B P h
4), basic salts such as tetramethylammonylumtitraphenylbore) (MeNBPha), and the like are used.

Among these, tetraalkylammonium hydroxides are particularly preferred.

(b) As the alkali metal compound, specifically, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, Potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium boroborophenide, and the like are used.

Further, (b) alkaline earth metal compounds include, specifically, calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate,
Barium bicarbonate, magnesium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate,
Stearic acid, calcium, barium stearate, magnesium stearate, strontium stearate, etc. are used.

(e) As boric acid or boric acid ester, boric acid or general formula B (OR) (OH) (formula n
In 3-n, R is alkyl such as methyl or ethyl, or aryl such as phenyl, and n is 1, 2 or 3).

Specifically, such boric acid esters include trimethyl borate, triethyl borate, tributyl borate,
Trihexyl borate, trihebutyl borate, triphenyl borate, tritolyl borate, trinaphthyl borate, etc. are used.

When the above-mentioned (a) nitrogen-containing basic compound is used, 1 mole of the aromatic organic trihydroxy compound is used.
0-6 to 10-1 mol, preferably 10-5 to 10''2
(b) If an alkali metal compound or alkaline earth metal compound is used, in an amount of 10 to 10-3 mol, preferably 10''7 to 10-4 mol, particularly preferably 10 to 10-4 -B is used in molar amounts, and (C) from 10 to 10 molar when boric acid or nistyl borate is used, preferably from 10 to
It is used in amounts of 10@-2 mol, particularly preferably from 10 to 10@-3 mol.

B (a) If the amount of the nitrogen-containing basic compound is less than 10-6 mol per 1 mol of the aromatic organic trihydroxy compound, the transesterification reaction and polymerization reaction will be slow, and therefore the alkali metal compound or alkaline earth metal The amount of the compound must be increased, and as a result, the hue, heat resistance, water resistance, etc. of the resulting polycarbonate tend to decrease,
On the other hand, if the amount exceeds 10 -1 mol, the hue and water resistance of the resulting polycarbonate tend to deteriorate.

and (b) the alkali metal compound or alkaline earth metal compound is 1 mole of the aromatic organic trihydroxy compound.
When the amount is less than 0-8 mol, the polymerization activity, especially the polymerization rate at high temperatures, tends to decrease significantly, while when it exceeds 10-3 mol, the polymerization activity improves, but the hue and heat resistance of the resulting polycarbonate decrease. , there is a tendency for water resistance to decrease.

In addition, if (C) boric acid or boric acid ester is less than 10-8 mol per mol of the aromatic organic trihydroxy compound, the molecular weight after heat aging tends to decrease significantly,
On the other hand, if the amount exceeds 10@-1 mol, the water resistance of the resulting polycarbonate tends to decrease.

In this way, (a) a nitrogen-containing basic compound, (b) an alkali metal compound or an alkaline earth metal compound, and (C) boric acid or a boric acid ester, (a) and (b)
, (a) and (c) , (b) and (c) or (
The catalyst consisting of a), (b) and (C) has high polymerization activity and can produce high molecular weight polycarbonate, and the resulting polycarbonate has excellent heat resistance and water resistance, and also has a good color tone. has been improved and has excellent transparency.

Next, the method for producing polycarbonate according to the present invention will be explained based on the drawings.

FIG. 1 is an example of a typical process diagram for carrying out the method for producing polycarbonate according to the present invention.

[First polycondensation reaction step] First, in a seed-type stirring tank 1 under nitrogen purging, as raw material monomers, for example, diphenyl carbonate, which is bisphenol A1 carbonate diester, which is an aromatic organic trihydroxy compound, is placed in a molten state. After introducing through the introduction pipes 2 and 3 (4 and 5 when using diphenyl terephthalate and diphenyl isophthalate, which are dicarboxylic acid esters), and thoroughly stirring and mixing these raw material monomers,
The monomer mixture in a molten state is supplied via a raw material transfer conduit 6 to a tank-type reaction tank 7 equipped with a vertical rotating shaft and a stirring blade attached to the vertical rotating shaft.

This tank-type reaction tank 7 is equipped with at least one turbine blade, paddle blade, anchor blade, helical ribbon blade, or a blade that is an improved version of these blades. In the present invention,
At least one such tank-type reaction tank is used.

In the tank-type reaction tank 7 whose temperature is controlled to start the transesterification reaction, a small amount of boric acid or boric acid ester dissolved in a monomer or phenol is continuously supplied to the tank-type reaction tank 7 via the catalyst introduction pipe 8. and stir.

Next, this reaction mixture is added through a catalyst introduction pipe 8° and a small amount of a nitrogen-containing basic compound and/or an alkali metal compound or an alkaline earth metal compound, while being passed through a preparation material transfer conduit 9 as described below. The reaction mixture is supplied to a tank-type reaction vessel 10 whose temperature and pressure conditions are controlled to be suitable for carrying out the first polycondensation reaction, and the reaction mixture is further reacted to obtain polycarbonate.

The reaction temperature in the first polycondensation reaction is usually 50 to 2
The temperature is 85°C, preferably in the range of 150 to 260°C, and the pressure can be reduced from normal pressure to 1 ms Hg. In this case, the lower limit pressure of the reduced pressure condition is 400 to 1 ms Hg, preferably 300 It can be set in the range of ~1 s+Hg.

In this first polycondensation reaction step, the intrinsic viscosity [η] determined by AI in a methylene chloride solution at 20°C is 0.01 to 0.4 d.
j! /g, preferably 0.03-0.4 dN /i
t, more preferably 0.05 to 0.35 dil/g.

Incidentally, the vapor of phenol produced as a by-product in this reaction and the vapor of some unreacted upper sludge are introduced into the distillation column 12 via a conduit 11, and are mixed with the refluxed phenol supplied via a conduit 13 for refluxed phenol. Rectify by contact. The rectified unreacted monomer is passed through a conduit 14 to a tank-type reaction tank 10.
will be supplied again. On the other hand, phenol vapor is introduced into a condenser 16 via a phenol vapor conduit 15 and condensed. A part of the condensed phenol is introduced into the distillation column 12 as reflux, and the remaining phenol is removed from the system via the phenol recovery conduit 17.

Further, uncondensed phenol is collected in a cold trap via a vent conduit 18.

In the reaction apparatus in which the reaction is carried out until the intrinsic viscosity [η] of the polycarbonate produced in the first polycondensation reaction step of the present invention reaches 0.3 d1/g, from the viewpoint of the color tone of the polycarbonate, the equipment constituting the reaction apparatus The surface material of the part of the component 7 such as piping that comes into contact with the raw monomer or the polymerization liquid (hereinafter referred to as the liquid contact part) occupies at least 90% or more of the total surface area of the liquid contact part, such as glass,
Preferably, the material is composed of one or more of nickel, tantalum, chromium, and Teflon. In the present invention, the surface material of the liquid-contacted part only needs to be composed of the above-mentioned substance, and the surface material may be a laminated material made of the above-mentioned substance and another substance, or a material in which the above-mentioned substance is plated with another substance. Can be used.

[Second Polycondensation Reaction Step] Next, the polycarbonate obtained in the first polycondensation reaction step is attached to a horizontal rotation shaft and approximately perpendicular to the horizontal rotation shaft via the prepolymer transfer conduit 19. and mutually discontinuous stirring blades, and when the length of the horizontal rotation axis is L and the rotational diameter of the stirring blade is D, L/D is 1.
15 to a horizontal agitating polymerization tank 20 to carry out a second polycondensation reaction as described later, by-produced phenol and partially unreacted motsumar are fed to a vent conduit 21. The polycondensation reaction is carried out by removing the polycondensate from the system.

This horizontal stirring polymerization tank 20 has one or more horizontal rotation shafts, and one stirring blade, such as a disk type, wheel type, seed type, frame type, window frame type, etc., is attached to the horizontal rotation axis. A horizontal high viscosity liquid processing device in which at least two or more stages of seeds or a combination of two or more kinds are installed per rotating shaft, and the surface of the reaction solution is renewed by stirring up or spreading the reaction solution using the stirring blades, In this specification, the term "surface renewal of the reaction solution" means that the reaction solution on the surface of the liquid is replaced with the reaction solution below the surface of the liquid. In the present invention, at least one such horizontal stirring polymerization tank is used.

The reaction temperature in the second polycondensation reaction is usually 240 to
320°C, preferably in the range of 250 to 290°C,
Also, the pressure is 3011■Hg or less, preferably 10+sg
+Hg or less, more preferably 2 amHg or less.

The horizontal stirring polymerization tank used in the present invention has two
Due to the large hold-up compared to vented extruders, it is possible to increase the residence time of the reaction mixture, thereby lowering the reaction conditions (particularly the temperature) and producing products with improved color and mechanical properties. It becomes possible to obtain excellent polycarbonate.

In this second polycondensation reaction step, the intrinsic viscosity [η] measured in a methylene chloride solution at 20°C is 0. 3-1.0dj
! /g, preferably from 0.33 to 0.9 dN/g, more preferably from 0.35 to 0.8 dN/g.

In the present invention, a twin-screw vent type extruder can be used after the polycondensation reaction is carried out in a horizontal stirring polymerization tank. When a twin-screw vented extruder is used in the present invention, the polycondensation reaction progresses considerably in the horizontal stirring polymerization tank at the front stage, so the reaction conditions of the twin-screw vented extruder can be relaxed, and the quality of the polycarbonate is improved. It becomes possible to prevent deterioration.

Effects of the Invention According to the present invention, a polycondensation reaction is carried out in a specific tank-type reaction tank while a mixture of an aromatic organic diacid group compound and a carbonic acid diester is melted, and a polycondensation reaction is carried out in a methylene chloride solution at 20°C. A first polycondensation reaction step to obtain a polycarbonate with an intrinsic viscosity [η] of 0.05 to 0.4 dl/lr as measured by Polycarbonate is produced through a second polycondensation reaction step in which a polycondensation reaction is carried out in a tank to obtain a polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 di/g, so it has excellent mechanical properties. A high molecular weight polycarbonate having a high molecular weight and an improved color tone can be obtained.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

First, the testing methods for the intrinsic viscosity [η], hue [b value], haze, light transmittance, Izot impact strength (notched) and terminal hydroxyl group concentration of the polymers obtained in Examples and Comparative Examples are shown below.

[Test method] (1) Intrinsic viscosity [η]: In methylene chloride (0.5d#
/sr) at 20°C using an Ubbelohde viscometer.

(2) Hue [b value]: The Lab value of a 2 mm thick press sheet is determined by Co1 orand Co1 of Nippon Denshoku Industrial View.
or DerrerenCe Meter ND-10
It was measured by a transmission method using 0ID, and the b value was used as a measure of yellowness.

(3) Haze, (4) Light transmittance: 1113 was determined using an automatic digital haze meter NDH-20D manufactured by Nippon Denshoku Kogyo ■ using a 2 mm thick press sheet.

(5) Izot impact strength (notched): rlFJ was determined using YSI-30 manufactured by Yonekura Co., Ltd. according to ^STM D 256 using a press plate with a thickness of 2 m+e.

(6) Terminal hydroxyl group concentration: 3 ml of 0.4 g sample
It was dissolved in chloroform and measured at 40°C using JEOL e$el7)'C-NMRGX-270.

Example 1 0.44 kg-mol of bisphenol A and 0.49 g-mol of diphenyl carbonate were placed in a 250-liter stirred tank, and after purging with nitrogen, they were dissolved at 140°C.

Next, the temperature was raised to 180°C, and 0.11 g of phosphoric acid was added.
Add mol and stir for 30 minutes. Then 0.11 g-mol of tetramethylammonium hydroxide and 0.003 g-mol of sodium bicarbonate were added as catalysts,
While raising the temperature to 260℃, gradually increase the pressure to 4
It was lowered to mm Hg. The amount of phenol distilled out was measured while keeping the temperature and pressure constant, and when there was no more phenol distilled out, the pressure was returned to atmospheric pressure with nitrogen. The time required for the reaction was 4 hours.

Next, this reactant was extracted from the bottom of the tank using a gear pump, passed through a die, and formed into a strand in a nitrogen atmosphere, and cut with a cutter to form a pellet. The intrinsic viscosity [η] of this prepolymer was 0.32.

Next, this prepolymer was added to a 2-shaft horizontal stirring polymerization tank (L/D-6,
The mixture was fed at a rate of 20 kg/hour using an extruder into a stirrer with a rotating diameter of 150 mm and an internal volume of 40 liters, and was polymerized for a residence time of 60 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.6
It was 2.

Other test results are shown in Table 1.

Example 2 Polymerization was carried out under the same conditions as in Example 1, except that 0.05 g-mol of halonic acid and 0.05 g-mol of tetramethylammonium hydroxide were used in Example 1 to obtain a polymer, The above tests were conducted on the obtained polymer.

The results are shown in Table 1.

Example 3 In Example 1, 2-carbomethoxyφ5-t-butylphenylphenyl carbonate was added as an end-capping agent at a ratio of 5 mol % to bisphenol A to the prepolymer obtained by a two-stage polymerization reaction. A polymer was obtained by polymerization under the same conditions as in Example 1, except that the mixture was added and mixed and fed into a twin-screw horizontal stirring polymerization tank using an extruder, and the above tests were conducted on the obtained polymer.

The results are shown in Table 1.

Example 4 Polymerization was carried out under the same conditions as in Example 1, except that paracumylphenol was mixed with bisphenol A as a raw material at a ratio of 5 mol% to bisphenol A as an end-capping agent. A polymer was obtained, and the above tests were conducted on the obtained polymer.

The results are shown in Table 1.

Comparative Example 1 Two-stage polymerization was carried out in the same manner as in Example 1 to obtain a prepolymer with an intrinsic viscosity [η] of 0.32.

This prepolymer was processed using a twin-screw vent extruder (35 mmL/
D-30 rotating in the same direction) at a rate of 5 kg/hour; at this time, the cylinder temperature was 280°C and the pressure at the vent part was 0.
It was controlled at 4 mmHg.

The residence time at this time was 4 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.46.

Other test results are shown in Table 1.

Comparative Example 2 In Comparative Example 1, 0.22 g-mol of boric acid and 0.22 g-mol of tetramethylammonium hydroxide were used as catalysts.
Polymerization was carried out under the conditions of Comparative Example 1, except that 0.006 g-mol of sodium bicarbonate was added, and the above tests were conducted on the obtained polymer.

The results are shown in Table 1.

Comparative Example 3 In Example 1, the pellets of the prepolymer obtained after the second stage polycondensation reaction were fed into a centrifugal thin film evaporator controlled at a temperature of 280° C. and a pressure of 0.4 mmHg using an extruder and reacted. . The intrinsic viscosity of the obtained polymer [
η] was 0.62.

Other test results are shown in Table 1.

[Brief explanation of the drawing]

FIG. 1 is an example of a typical process diagram for carrying out the method for producing polycarbonate according to the present invention. 1... Seed type stirring tank 2.3.4.5... Raw material introduction pipe 7... Seed type reaction t! 8,8°...Catalyst introduction pipe 10.
...Tank type reaction tank 12...Distillation column 16...Condenser 17...Phenol recovery conduit 18...Vent conduit 20...Horizontal stirring polymerization tank 21...Vent conduit 23. ...Twin-screw vent type extruder 24...Vent conduit 25...Outlet agent Patent attorney Shunichi Suzuki

Claims (1)

[Scope of Claims] 1) When producing polycarbonate by melt polycondensation of an aromatic organic dihydroxyl compound and a carbonic acid diester, the above monomer mixture is melted and attached to a vertical rotating shaft and the vertical rotating shaft. The polycondensation reaction was carried out by supplying the polycondensation reaction to at least one tank-type reaction tank equipped with a stirring blade, and the intrinsic viscosity [η
] is 0.05 to 0.4 dl/g, and the polycarbonate obtained in the first polycondensation step is
It has a horizontal rotation axis and mutually discontinuous stirring blades attached almost at right angles to the horizontal rotation axis, and when the length of the horizontal rotation axis is L and the rotation diameter of the stirring blade is D, L/
The polycondensation reaction is carried out by supplying to at least one horizontal stirring polymerization tank in which D is 1 to 15, and the above-mentioned intrinsic viscosity [η]
a second polycondensation reaction step to obtain a polycarbonate having a polycarbonate of from 0.3 to 1.0 dl/g.