JPH10251396A - Production of aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality aromatic polycarbonate excellent in mechanical properties free from discoloration at a high polymerization rate without using a large amount of an inert gas. SOLUTION: In this method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate by a melt method, the polymerization is carried out under reduced pressure by supplying 0.0001-0.1Nm<3> of an inert gas based on 1kg of a molten polymer fed to a polymerizer from plural inert gas feed openings installed based on one polymerizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an aromatic polycarbonate.

[0002]

2. Description of the Related Art In recent years, aromatic polycarbonates have been widely used in many fields as engineering plastics having excellent heat resistance, impact resistance and transparency. Various studies have hitherto been made on the method for producing the aromatic polycarbonate, and among them, an aromatic dihydroxy compound, for example, 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) and phosgene. Has been industrialized.

However, in this interfacial polycondensation method, toxic phosgene must be used, and the apparatus is corroded by by-produced hydrogen chloride and sodium chloride and a chlorine-containing compound such as methylene chloride used in large quantities as a solvent. In addition, there were problems such as difficulty in separating impurities such as sodium chloride and residual methylene chloride which adversely affect the physical properties of the polymer.

On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate, for example, bisphenol A and diphenyl carbonate are transesterified in a molten state, and polymerization is performed while extracting phenol by-produced. The law has been known for some time. The melting method is different from the interfacial polycondensation method,
While there are advantages such as not using a solvent, the viscosity of the polymer increases with the progress of polymerization, making it difficult to efficiently remove by-products such as phenol out of the system, making it difficult to increase the degree of polymerization. There was a problem.

Conventionally, various types of polymerizers have been known as polymerizers for producing an aromatic polycarbonate by a melting method. A method of using a vertical stirring tank type polymerization vessel equipped with a stirrer is generally widely known. However, a vertical stirred tank type polymerization vessel has the advantage of high volumetric efficiency and simplicity on a small scale, and can efficiently promote polymerization.On an industrial scale, however, as described above, with the progress of polymerization, There is a problem that it is difficult to efficiently extract by-product phenol to the outside of the system, and the polymerization rate becomes extremely low.

That is, in a large-scale vertical stirred tank type polymerization vessel, the ratio of the liquid volume to the evaporation area is generally larger than that in the case of a small-scale polymerization vessel, and the so-called liquid depth is large. In this case, even if the degree of vacuum is increased in order to increase the degree of polymerization, the lower part of the agitation tank is polymerized at a substantially high pressure due to the liquid depth, and phenol and the like are efficiently removed. It becomes difficult.

In order to solve this problem, various devices have been devised for extracting phenol and the like from a polymer in a high viscosity state. For example, in Japanese Patent Publication No. 50-19600, a method using a screw type polymerizer having a vent portion, in Japanese Patent Publication No. 52-36159, a method using an interlocking twin-screw extruder, and in Japanese Patent Publication No. 53-5718, A method using a thin-film evaporator, for example, a screw evaporator or a centrifugal thin-film evaporator, is described. Further, JP-A-2-153923 discloses that a centrifugal thin-film evaporator is used in combination with a horizontal stirring polymerization tank. A method is specifically disclosed. Japanese Patent Application Laid-Open No. 7-292597 discloses that a high-quality aromatic polycarbonate without coloring can be produced at a high polymerization rate by a method of polymerizing while freely falling from a perforated plate. A method of polymerizing while falling is also described. The publication also describes an example in which a small amount of an inert gas is supplied into the polymerization system.

[0008] In producing an aromatic polycarbonate by a melting method, a method for carrying out polymerization in the presence of an inert gas is widely known. For example, US Pat. No. 2,964,297
No. 3,153,008 describe a method for producing an aromatic polycarbonate by a transesterification method using an inert gas under reduced pressure in order to avoid an oxidative secondary reaction. A small amount of an inert gas with respect to the aromatic polycarbonate is supplied into the polymerization vessel. On the other hand, as a method of using a large amount of inert gas to extract phenol and the like out of the polymerization system, Japanese Patent Application Laid-Open No.
No. 6997 describes a method for producing an aromatic polycarbonate by passing an oligocarbonate melt together with an inert gas of 1 m ³ or more per kg of oligocarbonate through a heating tube under normal pressure or under pressure. However, in the method for producing an aromatic polycarbonate using a large amount of inert gas, when the inert gas used for polymerization is repeatedly used for polymerization, it is necessary to separate the aromatic monohydroxy compound in the inert gas. Arises
Large separation equipment is required.

In Japanese Patent Application No. Hei 8-21003, the inventors of the present invention have proposed that, when polymerizing while dropping along a guide in a space under the flow of an inert gas, aromatic monomer contained in the inert gas is used. The range of the partial pressure ratio of the hydroxy compound to the inert gas was specified, and a method was proposed in which the facility for collecting the inert gas was not excessive. The present inventors have further studied a method of producing a high-quality polycarbonate excellent in mechanical properties by using a small amount of an inert gas to remarkably increase the polymerization rate.

[0010]

When an aromatic polycarbonate is produced by a melting method which does not have a problem of separation of impurities and residual methylene chloride, a high-quality aromatic polycarbonate which is free from coloring and has excellent mechanical properties is highly polymerized. It is an object of the present invention to provide a method for producing by industrially preferable means at a high speed without using a large amount of inert gas.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the purpose can be achieved with a small amount of inert gas by using a specific method. The present invention has been completed. That is, the present invention is as follows. (1) A method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate by a melting method, wherein at least one polymerization vessel has a plurality of inert gas supply ports and a molten polymer supplied to the polymerization vessel 0.0001 to 0.1 inert gas per 1 kg
A method for producing an aromatic polycarbonate, wherein the polymerization is performed under a reduced pressure by supplying the mixture to the polymerization reactor through a plurality of inert gas supply ports within a range of Nm ³ . (2) The production of the aromatic polycarbonate according to the above (1), wherein the polymerization vessel having a plurality of inert gas supply ports is a polymerization vessel in which the polymer is melted down along the support to progress the polymerization. Method.

Conventionally, when an aromatic polycarbonate is to be produced by efficiently extracting phenol or the like using an inert gas, the inert gas is usually supplied from a single inert gas supply port to the space of the polymerization vessel. In the case where an inert gas is supplied into a molten polymer, only a method of using a large amount of the inert gas and polymerizing under normal pressure or pressure is known. Surprisingly, a small amount of inert gas is supplied from a plurality of inert gas supply ports provided per polymerization reactor, and polymerization is performed under reduced pressure, thereby supplying an inert gas from one supply port. It has been clarified that the polymerization rate is remarkably increased as compared with the case, and an aromatic polycarbonate having excellent mechanical properties such as tensile elongation can be obtained. The reason for this is not clear, but by supplying and mixing the inert gas from multiple supply ports,
It is presumed that the surface state of the molten polymer under reduced pressure conditions is made uniform and the polymerization rate is increased, and the resulting aromatic polycarbonate is also a polymer having excellent uniform mechanical properties.

Hereinafter, the present invention will be described in detail. In the present invention, the aromatic dihydroxy compound is a compound represented by the following formula. HO-Ar-OH (wherein, Ar represents a divalent aromatic group). The divalent aromatic group Ar is preferably, for example, one represented by the following formula. -Ar ¹ -Y-Ar ^2- (wherein, Ar ¹ and Ar ² each independently represent a divalent carbocyclic or heterocyclic aromatic group having 5 to 70 carbon atoms, and Y represents carbon Represents a divalent alkane group having the numbers 1 to 30).

In the divalent aromatic groups Ar ¹ and Ar ² ,
One or more hydrogen atoms having no adverse effect on the reaction, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group,
It may be substituted by a phenoxy group, vinyl group, cyano group, ester group, amide group, nitro group, or the like.

Preferred specific examples of the heterocyclic aromatic group include an aromatic group having one or more ring-forming nitrogen, oxygen or sulfur atoms. The divalent aromatic groups Ar ¹ and Ar ² represent groups such as substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and substituted or unsubstituted pyridylene. The substituent here is as described above.

The divalent alkane group Y is, for example,
Is an organic group represented by

[0017]

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(Wherein R ¹ , R ² , R ³ , and R ⁴ each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms,
10 alkoxy groups, a cycloalkyl group having 5 to 10 ring carbon atoms, a carbocyclic aromatic group having 5 to 10 ring carbon atoms,
Represents a carbocyclic aralkyl group having 6 to 10 carbon atoms. k is 3
And R ⁵ and R ⁶ are independently selected for each X, independently of one another, hydrogen or C 1
And X represents an alkyl group, and X represents carbon. Also,
In R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ , other substituents such as a halogen atom and an alkyl having 1 to 10 carbon atoms are used as long as one or more hydrogen atoms do not adversely affect the reaction. It may be substituted by a group, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, a nitro group, or the like. Examples of such a divalent aromatic group Ar include those represented by the following formula (2).

[0019]

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(Wherein R ⁷ and R ⁸ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cyclo group having 5 to 10 ring carbon atoms) An alkyl group or a phenyl group, m and n
Is an integer of 1 to 4, and when m is 2 to 4, each R ⁷ may be the same or different, and n is 2 to 4
In this case, each R ⁸ may be the same or different. Further, the divalent aromatic group Ar may be represented by the following formula. —Ar ¹ —Z—Ar ² — (wherein, Ar ¹ and Ar ² are as described above, and Z is a single bond or —O—, —CO—, —S—, —SO ₂ —, —SO—,
^{-COO -, - CON (R 1} ) - represents a divalent group, such as. Here, R ¹ is as described above. Examples of such a divalent aromatic group Ar include those represented by the following chemical formula (3).

[0021]

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(In the formula, R ⁷ , R ⁸ , m and n are as described above.) The aromatic dihydroxy compound used in the present invention may be a single kind or two or more kinds. A typical example of the aromatic dihydroxy compound is bisphenol A. The diaryl carbonate used in the present invention is represented by the following chemical formula 4.

[0023]

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(Wherein, Ar ³ and Ar ⁴ each represent a monovalent aromatic group.) Ar ³ and Ar ⁴ each represent a monovalent carbocyclic or heterocyclic aromatic group. ³ , in Ar ⁴ , one or more hydrogen atoms has another substituent that does not adversely affect the reaction;
For example, a halogen atom, an alkyl group having 1 to 10 carbon atoms,
It may be substituted by an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, a nitro group, or the like. A
r ³ and Ar ⁴ may be the same or different.

Representative examples of the monovalent aromatic groups Ar ³ and Ar ⁴ include a phenyl group, a naphthyl group, a biphenyl group and a pyridyl group. These may be substituted with one or more substituents described above. Preferred Ar ³
And Ar ⁴ include, for example, those shown in the following Chemical Formula 5, respectively.

[0026]

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A typical example of a diaryl carbonate is represented by the following formula (6).

[0028]

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(Wherein R ⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms,
An alkoxy group having 10; a cycloalkyl group having 5 to 10 ring carbon atoms; or a phenyl group;
When p is 2 or more, each R ⁹ may be different, and when q is 2 or more,
Each R ¹⁰ may be different. Among these diaryl carbonates, unsubstituted diphenyl carbonate, ditolyl carbonate, di-t
Symmetric diaryl carbonates, such as lower alkyl-substituted diphenyl carbonates such as -butylphenyl carbonate, are preferred, with diphenyl carbonate being the simplest diaryl carbonate being particularly preferred.

These diaryl carbonates may be used alone or in combination of two or more. The use ratio (charge ratio) of the aromatic dihydroxy compound and the diaryl carbonate varies depending on the type of the aromatic dihydroxy compound and the diaryl carbonate used, the polymerization temperature and other polymerization conditions, but the diaryl carbonate is used in 1 mol of the aromatic dihydroxy compound. On the other hand, usually 0.9 to 2.5 mol, preferably 0.95 to
2.0 moles, more preferably 0.98 to 1.5 moles.

The number average molecular weight of the aromatic polycarbonate obtained by the method of the present invention is usually in the range of 500 to 100,000, preferably in the range of 2000 to 30,000. The aromatic polycarbonate of the present invention is a method of performing polycondensation from an aromatic dihydroxy compound and a diaryl carbonate as described above by transesterification in a molten state while heating in the presence or absence of a catalyst, The polymerization vessel is not particularly limited. For example, a stirred tank reactor, a thin film reactor, a centrifugal thin film evaporation reactor, a surface-renewal twin-screw kneading reactor, a twin-screw horizontal stirring reactor, a wet-wall reactor, and a perforated plate that allows free fall polymerization A polymerization vessel is used in which a polymer is melted and dropped along a reactor and a support to promote polymerization, and a polymerization vessel in which these are used alone or in combination is used. The polymerizer that allows the polymer to melt and flow along the support to progress the polymerization does not have a stirring shaft, and thus is preferable in that air is not mixed in from the stirring driving unit and maintenance is easy. Further, a polymerizer that melts and flows down the polymer along the support to advance the polymerization is composed of 1
It has been clarified that the effect of increasing the polymerization rate by introducing an inert gas from a plurality of inert gas supply ports per unit is larger than that of other types of polymerization vessels. Although the reason for this is not clear, the polymerization vessel in which the polymer is melted down along the support to promote the polymerization has a relatively large evaporation area of the aromatic monohydroxy compound as compared with other types of polymerization vessels, It is considered that the effect of increasing the polymerization rate by changing the state of the evaporation surface of the inert gas is increased. In this case, the support may have various shapes such as a flat shape, a cylindrical shape, a conical shape, and a chain shape. The support is hollow, polymerizing while dropping the polymer outside the support, a method of putting a heating medium into the hollow part, polymerizing while dropping the polymer into the hollow part of the support, polymerizing outside the support It is also possible to use a method in which a heating medium is put into the container.

In the early stage of the polymerization, a molten polymer is produced from an aromatic dihydroxy compound and a diaryl carbonate using a vertical stirring tank, and the molten polymer is subjected to a surface renewal type biaxial kneading reactor and a biaxial horizontal stirring reactor. A method of polymerizing using a wet-wall reactor, a perforated plate reactor that polymerizes while allowing it to fall freely, a polymerizer that melts and drops a polymer along a support, and proceeds with polymerization, etc., is preferred for the present invention. This is one of the embodiments. In the present invention, the molten polymer supplied to the polymerization vessel is a molten mixture of an aromatic dihydroxy compound and a diaryl carbonate, or a melt in the course of polymerization produced from an aromatic dihydroxy compound and a diaryl carbonate, Means the molten polymer in the mouth.

In the method for producing an aromatic polycarbonate of the present invention, at least one polymerization vessel has a plurality of inert gas supply ports, and the polymerization is performed by supplying an inert gas from the inert gas supply ports. is required. There is no particular limitation on the polymerization reactor, and examples thereof include a surface-renewal-type twin-screw kneading reactor, a twin-screw horizontal stirring reactor, a wet-wall reactor, a perforated-plate reactor that allows free-fall polymerization, and a support. Any polymerizer such as a polymerizer that melts and drops the polymer to progress the polymerization can be used, but a polymerizer that melts the polymer along the support and advances the polymerization is preferable.

In the present invention, the inert gas is supplied in an amount of 0.0001 to 1 kg of the molten polymer supplied to the polymerization vessel.
In a range of 0.1 Nm ³ , the polymerization is performed under reduced pressure by supplying a plurality of inert gas supply ports per polymerization reactor to the polymerization reactor. Specific examples of the inert gas include nitrogen, argon, helium, carbon dioxide and a lower hydrocarbon gas, and nitrogen is particularly preferred. The amount of the inert gas is 0.00 to 1 kg of the molten polymer supplied to the polymerization vessel.
When it is less than 01 Nm ^{3, the} effect of increasing the polymerization rate is small, and when it is more than 0.1 Nm ³ , equipment for separating an aromatic monohydroxy compound and the like from an inert gas becomes too large, which is not industrially preferable. The more preferable amount of the inert gas supply per 1 kg of the molten polymer supplied to the polymerization vessel is in the range of 0.0001 to 0.08 Nm ³ , and the more preferable amount is in the range of 0.0002 to 0.06 Nm ³ . The number of inert gas supply ports provided in one polymerization vessel is usually 2 to 1000, preferably 3 to 5
00, more preferably 4 to 100. When the number of the supply ports is one, the effect of increasing the polymerization rate by the inert gas is small, and the tensile elongation of the obtained aromatic polycarbonate is lower than that in the case where the number of the supply ports is two or more.
Further, when the number of the inert gas supply ports is more than 1000, it is not preferable because the equipment becomes large and complicated. The position of the inert gas supply port may be either in the gas phase of the polymerization vessel or in the liquid phase of the molten polymer, but when the gas is supplied in the gas phase, a nozzle provided on the outer periphery of the polymerization vessel, It is preferable that the nozzle inserted in the inside be a supply port. Supplying the heated inert gas to the polymerization vessel is a preferred embodiment of the present invention.

In the present invention, the polymerization is carried out under reduced pressure. The preferred pressure varies depending on the type and molecular weight of the aromatic polycarbonate to be produced, the polymerization temperature, and the like. For example, when producing an aromatic polycarbonate from bisphenol A and diphenyl carbonate, the number average molecular weight is 1
660 Pa (50 mmHg) in the range of 000 or less
~ 53280 Pa (400 mmHg) is preferred, and when the number average molecular weight is
00Pa (3mmHg)-6660Pa (50mmHg)
g) is preferable, and when the number average molecular weight is in the range of 2,000 or more, 2670 Pa (20 mmHg) or less, particularly 1
330 Pa (10 mmHg) or less is preferable, and
0 Pa (3 mmHg) or less is preferable.

The transesterification reaction can be carried out without adding a catalyst, but is carried out in the presence of a catalyst if necessary in order to increase the polymerization rate. The polymerization catalyst is not particularly limited as long as it is used in this field, and hydroxides of alkali metals and alkaline earth metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide are used. Alkali metal salts, alkaline earth metal salts, quaternary ammonium salts of hydrides of boron and aluminum such as lithium aluminum hydride, sodium borohydride, tetramethylammonium borohydride; lithium hydride, sodium hydride , Alkali metal and alkaline earth metal hydrogen compounds such as calcium hydride; lithium methoxide, sodium ethoxide,
Alkoxides of alkali metals and alkaline earth metals such as calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide, L
Alyloxides of alkali metals and alkaline earth metals such as iO-Ar-OLi and NaO-Ar-ONa (Ar is an aryl group); organic metals of alkali metals and alkaline earth metals such as lithium acetate, calcium acetate and sodium benzoate Acid salts; zinc compounds such as zinc oxide, zinc acetate, zinc phenoxide; boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, (R ¹ R ² R ³ R ⁴ ) Ammonium borates or phosphonium borates (R ¹ , R ² ) represented by NB (R ¹ R ² R ³ R ⁴ ) or (R ¹ R ² R ³ R ⁴ ) PB (R ¹ R ² R ³ R ⁴ ) ,
R ³ and R ⁴ are as described in Chemical formula 1. ); Silicon compounds such as silicon oxide, sodium silicate, tetraalkylsilicon, tetraarylsilicon, diphenyl-ethyl-ethoxysilicon; germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide and the like Compounds of germanium: tin compounds such as tin oxide, dialkyltin oxide, dialkyltin carboxylate, tin acetate, ethyltin tributoxide, and other tin compounds combined with alkoxy or aryloxy groups, tin compounds such as organotin compounds; lead oxide Compounds of lead, such as lead acetate, lead carbonate, basic carbonate, alkoxide or aryloxide of lead and organic lead; quaternary ammonium salts, quaternary phosphonium salts,
Onium compounds such as quaternary arsonium salts; antimony compounds such as antimony oxide and antimony acetate; manganese compounds such as manganese acetate, manganese carbonate and manganese borate; titanium such as titanium oxide, titanium alkoxide or aryloxide And catalysts such as zirconium acetate, zirconium oxide, zirconium alkoxide or aryloxide, and zirconium compounds such as zirconium acetylacetone.

When a catalyst is used, these catalysts may be used alone or in combination of two or more. The amount of these catalysts to be used is generally selected in the range of 10 ^-8 to 1% by weight, preferably 10 ^-7 to 10 ^-1 % by weight, based on the aromatic dihydroxy compound as the raw material. There are no particular restrictions on the material of the polymerization vessel or piping that achieves the method of the present invention, and it is usually selected from stainless steel, nickel, glass lining, and the like.

The present invention is easy to scale up,
It is particularly preferably used in industrial processes of 100 tons / year or more, preferably 1000 tons / year or more, more preferably 10,000 tons / year or more.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to examples. Note that the molecular weight is a number average molecular weight (hereinafter, referred to as M) measured by gel permeation chromatography (GPC).
Abbreviated as n. ). The collar was CIELA using a 3.2 mm thick test piece obtained by injection molding at 280 ° C.
The yellowness was measured by the B method and indicated by the b ^* value. The tensile elongation was measured according to ASTM D638 using a 3.2 mm thick test piece obtained by injection molding at 280 ° C.

[0040]

Example 1 A reaction was carried out using a polymerization vessel 7 having a plurality of columnar supports 4 as shown in FIGS. 1 (a) and 1 (b). FIG. 1A is a vertical cross-sectional view of a polymerization vessel.
(B) is a horizontal sectional view of the polymerization vessel. This polymerization vessel 7 is made of SUS3 having an inner diameter of 0.5 m, a thickness of 1 mm, and a length of 8 m.
A 70L 16L columnar support 4 is provided.
The melted polymer supplied to 0 is uniformly distributed to each support 4 by the dispersion plate 3. Four inert gas supply ports 5 (5 ') are provided in the lower part of the polymerization vessel, and a vacuum vent port 6 is provided in the upper part of the polymerization vessel. The outside of the polymerization vessel 7 is a jacket, and is heated by a heating medium.

In this polymerization vessel, bisphenol A and diphenyl carbonate (a molar ratio of bisphenol A to 1.0 was used).
The molten polymer of the aromatic polycarbonate having Mn6000 produced from 5) was added to the molten polymer supply pipe 1 by 50.
kg / hr continuously at 260 ° C, pressure 6
Polymerization was performed under conditions of 7 Pa (0.5 mmHg) while continuously extracting the aromatic polycarbonate from the outlet. Nitrogen was supplied from the four inert gas supply ports 5 (5 ') at a rate of 70 normal liters / hr for a total of 280 normal liters / hr. After 50 hours, the aromatic polycarbonate discharged from the discharge port was Mn11700, and had a good color (b ^* value of 3.3). The tensile elongation was 98%. The amount of nitrogen per kg of molten polymer is 0.0056 Nm ³ . The results are summarized in Table 1.

[0042]

Examples 2 to 4 Aromatic polycarbonates were produced in exactly the same manner as in Example 1 except that the number of the inlets for the inert gas was different and various polymerization reactors were used. The results are summarized in Table 1.

[0043]

COMPARATIVE EXAMPLE 1 An aromatic polycarbonate was produced in the same manner as in Example 1 except that the number of the inlets for the inert gas was different and various polymerization reactors were used. The results are summarized in Table 1.

[0044]

Examples 5 to 9 An aromatic polycarbonate was produced in exactly the same manner as in Example 1 except that the flow rate of nitrogen was different. The results are summarized in Table 1.

[0045]

Comparative Examples 2-3 An aromatic polycarbonate was produced in exactly the same manner as in Example 1 except that the flow rate of nitrogen was different. The results are summarized in Table 1.

[0046]

[Embodiment 10] Argon was supplied from each supply port in place of nitrogen.
An aromatic polycarbonate was produced in exactly the same manner as in Example 1, except that 0 normal liter / hr was supplied, for a total of 280 normal liter / hr. After 50 hours, the Mn of the aromatic polycarbonate discharged from the discharge port was 11600.
And a good color (b ^* value of 3.3).

[0047]

Examples 11 to 12 Using the same apparatus as in Example 1, the fragrance was varied by variously changing the Mn of the molten polymer to be supplied, the polymerization temperature, the pressure, and the amount of nitrogen supplied from the gas supply port 2 to the molten polymer supply pipe. A group polycarbonate was produced. Table 2 summarizes the results.

[0048]

Comparative Example 4 Example 1 except that the nitrogen supply amount was changed.
Aromatic polycarbonate was produced exactly as in 2. Table 2 summarizes the results.

[0049]

Example 13 An aromatic polycarbonate was produced in exactly the same manner as in Example 11 except that the number of the inert gas supply ports was different. Table 2 summarizes the results.

[0050]

Comparative Example 5 An aromatic polycarbonate was produced in exactly the same manner as in Example 11 except that the number of inlets for the inert gas was different. Table 2 summarizes the results.

[0051]

Embodiment 14 Two stirring shafts having a rotating diameter of 0.4 m are provided.
1.5m internal volume^ThreeExample 1 was placed in a horizontal stirring tank having a length of 4 m.
Polymerization is performed by continuously supplying the same molten polymer as in Step 2.
Was. The supply amount of the molten polymer, the polymerization temperature, and the polymerization pressure
Exactly the same as Example 12. The rotation speed of the stirring shaft is 15r
pm. The four inert gas supplies provided at the top of the polymerization vessel
Nitrogen was supplied from the supply port in the same amount as in Example 12. 50 hours
M of aromatic polycarbonate discharged from the polymerization vessel later
n is 10100 and b^*The value is 3.6 and the tensile elongation is 9
1%. The amount of nitrogen per 1 kg of molten polymer is
0.0008 Nm ^ThreeIn.

[0052]

Comparative Example 6 An aromatic polycarbonate was produced in the same manner as in Example 14 except that nitrogen was not supplied. 50
After an hour, the Mn of the aromatic polycarbonate discharged from the discharge port was 8,700, the b ^* value was colored at 4.0, and the tensile elongation was 80%.

[0053]

Example 15 The same procedure as in Example 1 was carried out except that a molten polymer of Mn6000 produced from 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane was used instead of bisphenol A. The reaction was performed under the conditions. The aromatic polycarbonate discharged from the outlet after 50 hours was Mn11100, a good color (b ^* value of 3.3), and the tensile elongation was 94%. The amount of nitrogen per kg of molten polymer is 0.005.
6 Nm ³ .

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

According to the present invention, a high-quality aromatic polycarbonate having excellent mechanical properties without coloring can be produced at a high polymerization rate by an industrially preferable means without using a large amount of inert gas. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view in the vertical direction of an example of a polymerization vessel that can be used in the present invention, and FIG. 1B is a schematic cross-sectional view in the horizontal direction of an inert gas supply port.

[Explanation of symbols]

 1. 1. molten polymer supply port 2. molten polymer at the bottom of the polymerization vessel Dispersion plate 4. 5. Columnar support 5, 5 'inert gas supply port 6. Vacuum vent port Polymerizer 8. Discharge pump 9. Vent

Claims (2)

[Claims] 1. A method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate by a melting method, wherein at least one polymerization vessel has a plurality of inert gas supply ports and supplies the gas to the polymerization vessel. Inert gas from 0.0001 to 1 kg of molten polymer
A method for producing an aromatic polycarbonate, comprising supplying to the above-mentioned polymerization vessel from a plurality of inert gas supply ports within a range of 0.1 Nm ³ to carry out polymerization under reduced pressure. 2. The aromatic polycarbonate according to claim 1, wherein the polymerizer having a plurality of inert gas supply ports is a polymerizer in which a polymer is caused to melt and flow down along a support to progress polymerization. Manufacturing method.