JPH107783A - Production of aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process whereby a high-quality arom. polycarbonate is produced without increasing the load on an extruder and without casing filter clogging by properly adjusting a transfer pipeline. SOLUTION: In producing an arom. polycarbonate by the melt polymn. of an arom. dihydroxy compd. and a diaryl carbonate with at least one polymerizer, the pipeline for transferring a melted polymer having a number average mol.wt. of 4,000 or higher is adjusted to have an average gradient of 1% or higher downflow gradient and to satisfy the relation: A/(A+B+C+ D)>0.9 (wherein A is the length of the part of the pipeline with a downflow gradient of 1% or higher; B is the length of the part with a downflow gradient lower than 1%; C is the length of the horizontal part; and D is the length of the part with an upflow gradient). The total length of the pipeline is pref. 15m or lower.

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. In particular, recently, the use as a substrate material of an optical disk is rapidly expanding. As for the production method of the aromatic polycarbonate, various polymerization methods have been studied. Among them, an interfacial polycondensation method of reacting phosgene with an alkaline aqueous solution of an aromatic dihydroxy compound such as 2,2'-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) in the presence of an organic solvent is known. It is known. The organic solvent used in this method is a halogen-based organic solvent, for example, methylene chloride, chlorobenzene, or the like is used. In particular, methylene chloride is mainly used. However, in this method, it is difficult to completely remove the organic solvent from the obtained polymer, and mold corrosion or coloring due to the halogen derived from the remaining organic solvent occurs, which has an unfavorable effect on later uses. In particular, when an aromatic polycarbonate is used as the substrate of the optical disk, the residual halogen is a fatal problem in that the recording film is corroded and causes an error.

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. Polycondensation methods are known. Unlike the interfacial polycondensation method, the melt polycondensation method has advantages such as not using a solvent.On the other hand, it is difficult to obtain a good color polymer without coloring, and the viscosity of the molten polymer is high. However, there is a problem that it is difficult to remove foreign matter, especially optical minute foreign matter, from the polymer. Such optical minute foreign matter is not preferable because it causes an error when used for optical applications, particularly for optical disks and the like.

Heretofore, various methods have been disclosed for producing an aromatic polycarbonate with less foreign matter by a melt polycondensation method. For example, JP-A-5-239334 discloses that after an aromatic dihydroxy compound and a carbonic acid diester are melt-polycondensed in the presence of a catalyst, an additive is added while the polycarbonate as a reaction product is in a molten state. It is described that an optical polycarbonate having few foreign substances can be produced by kneading and, in some cases, kneading and filtering with a polymer filter. However, even though this method can reduce relatively large foreign matter of 1 μm or more, it is difficult to sufficiently reduce fine foreign matter of 1 μm or less. In addition, using a polymer filter having an absolute filtration accuracy of 1 μm or less is not practical because the load on the extruder becomes extremely large due to the high melt viscosity of polycarbonate, and the clogging is rapid. In fact, the polymer filter used in the examples has a filtration accuracy of 5 μm,
There is no description of the amount of foreign matter below m. JP-A-6-234845 discloses that at least two reactors are used in series to melt-polycondensate an aromatic dihydroxy compound and a carbonic acid diester before and after the final reactor and at the outlet of the final reactor, respectively. A method of providing at least one filter is described. Also in this publication, the absolute filtration accuracy of the filter provided at the outlet of the final reactor is 5
It is not less than μm, and it is not possible to reduce minute foreign matter of 1 μm or less. Also, in JP-A-7-207015,
It has been shown that by polymerizing an aromatic dihydroxy compound and a diaryl carbonate in the presence of lithium phthalimide or the like, side reactions are suppressed, and generation of insoluble foreign matter due to a branching reaction is suppressed. However, even in this publication, the generation of foreign substances of 1 μm or more can be suppressed, but the fine foreign substances of 1 μm or less cannot be sufficiently reduced.

[0005] That is, heretofore, no method has been known for producing an aromatic polycarbonate having a small amount of fine foreign matter of 1 µm or less by a melt polycondensation method.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing an aromatic polycarbonate by a melt polycondensation method, which is capable of producing a high-quality aromatic polycarbonate having little coloring and little foreign matter without increasing the load on an extruder. It is another object of the present invention to provide a method for producing a filter without causing a problem of filter clogging.

[0007]

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 an appropriate piping for transporting an aromatic polycarbonate prepolymer having a specific molecular weight or more and / or an aromatic polycarbonate is appropriate. The present inventors have found that the object can be achieved by the conversion, and have completed the present invention.

That is, the present invention is as follows. (A) When producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate using one or two or more polymerization vessels, a molten polymer having a number average molecular weight of 4000 or more is transferred. The average flow rate of the pipe is 1% or more, and the length of the down flow pipe is 1% or more (A), and the length of the down flow pipe is less than 1% (B). Aromatic polycarbonate characterized in that the relationship between the length of horizontal pipe (C) and the length of upflow pipe (D) satisfies the following formula: 1 A / (A + B + C + D)> 0.9 (1) Recipe.

(B) The total distance of piping for transferring a molten polymer having a number average molecular weight of 4000 or more is 15
m or less, the process for producing an aromatic polycarbonate according to (a). (C) When producing an aromatic polycarbonate by polymerizing in a molten state from one or two or more polymerizers from an aromatic dihydroxy compound and a diaryl carbonate, the reaction rate of the aromatic dihydroxy compound is 5 to 90%. In a pipe for removing foreign substances having a size of 1 μm or less present in an aromatic polycarbonate prepolymer, and transferring a molten polymer having a number average molecular weight of 4000 or more, an average gradient of the pipe is 1% or more. Length of downflow pipe with downflow and slope 1% or more (A), length of downflow pipe with slope less than 1% (B), length of horizontal pipe (C), length of upflow pipe A method for producing an aromatic polycarbonate, characterized in that the relationship of (D) satisfies the following formula: 1 A / (A + B + C + D)> 0.9 (1)

Heretofore, the mixing path or generation path of the minute foreign matter has been hardly clarified. In order to reduce the foreign matter, a method of removing the foreign matter generated by a filter has been mainly used. However, as a result of intensive studies by the present inventors, unexpectedly, the gradient of a pipe for transferring a molten polymer having a number average molecular weight of 4000 or more is involved in the generation of fine foreign matter, and by optimizing this, the fine foreign matter is reduced. It has been clarified that high-quality aromatic polycarbonate with less generation and less coloring can be produced.

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

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

[0015]

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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).

[0017]

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(Wherein R ⁷ and R ⁸ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a cycloalkyl 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. ) Furthermore, the divalent aromatic group Ar is -Ar ¹ -Z-Ar ²
-May be indicated.

(Where Ar ¹ and Ar ² are as described above,
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 formula (3).

[0020]

Embedded image

(Wherein R ⁷ , R ⁸ , m and n are as described above.) Further, specific examples of the divalent aromatic group Ar include substituted or unsubstituted phenylene, substituted or unsubstituted Examples include substituted naphthylene, substituted or unsubstituted pyridylene, and the like. 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
Examples of Ar ⁴ and Ar ⁴ include, for example,

[0026]

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Representative examples of the diaryl carbonate include substituted or unsubstituted diphenyl carbonates 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 diphenyl 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 5,000 to 100,000.
And preferably in the range of 5,000 to 30,000. The aromatic polycarbonate of the present invention is obtained by transesterifying the above aromatic dihydroxy compound and diaryl carbonate in a molten state while heating under reduced pressure and / or inert gas flow in the presence or absence of a catalyst. This is a method of performing polycondensation by a reaction, and 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 reactor, a perforated plate reactor with a wire, which polymerizes while being dropped along a wire, or the like, is used alone or in combination. It is also preferable to use an extruder, a polymer mixer, or the like in combination with a polymerizer as a device for adding a stabilizer, an additive, and the like while the aromatic polycarbonate is in a molten state after the polymerization.

In the present invention, in producing the aromatic polycarbonate by reacting the aromatic dihydroxy compound with the diaryl carbonate, the reaction temperature is usually selected from the range of 50 to 350 ° C., preferably 150 to 290 ° C. It is. As the reaction proceeds, an aromatic monohydroxy compound is produced, and by removing this compound from the reaction system, the reaction rate can be increased. Therefore, by introducing an inert gas such as nitrogen, argon, helium, carbon dioxide or a lower hydrocarbon gas which does not adversely influence the reaction, the generated aromatic monohydroxy compound is removed together with these gases. And a method of performing the reaction under reduced pressure are preferably used. The preferred reaction pressure depends on the molecular weight, and is 10 mmH at the beginning of polymerization.
g to normal pressure, and 20 mmH
g, especially 10 mmHg or less, preferably 2 mmHg
It is more preferable to set the following.

Although the melt polycondensation reaction can be carried out without adding a catalyst, it 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, but hydroxides of alkali metals or 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 , Calcium hydride and other alkali metal or alkaline earth metal hydrides; lithium methoxide, sodium ethoxide, calcium methoxide and other alkali metal or alkaline earth metal alkoxides; lithium phenoxide, sodium phenoxide, magnesium phenoxide Kishido, LiO-Ar-OLi, NaO-Ar-ONa (A
r is an aryl group) alkali metal or alkaline earth metal aryloxide; alkali metal or alkaline earth metal organic acid salts such as lithium acetate, calcium acetate, sodium benzoate; zinc oxide, zinc acetate, zinc phenoxide, etc. Zinc compounds; boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate, triphenyl borate, (R ¹ R ² R ³ R ⁴ ) NB (R ¹ R ²
An ammonium borate represented by (R ³ R ⁴ ), (R ¹ R ² R ³
R ⁴ ) Boron compounds such as phosphonium borates represented by PB (R ¹ R ² R ³ R ⁴ ) (R ¹ , R ² , R ³ and R ⁴ are as described in the above formula 1) Silicon oxide, sodium silicate,
Silicon compounds such as tetraalkylsilicon, tetraarylsilicon, diphenyl-ethyl-ethoxysilicon; germanium compounds such as germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide; tin oxide, dialkyltin oxide, dialkyltin Tin compounds such as tin compounds and organic tin compounds bonded to alkoxy or aryloxy groups such as carboxylate, tin acetate and ethyltin tributoxide; lead oxide, lead acetate, lead carbonate, basic carbonate, lead and organic compounds Lead compounds such as alkoxides or aryloxides of lead; onium compounds such as quaternary ammonium salts, quaternary phosphonium salts, and quaternary arsonium salts; antimony compounds such as antimony oxide and antimony acetate; acetic acid Manganese compounds such as manganese, manganese carbonate and manganese borate; titanium compounds such as titanium oxide, titanium alkoxide or aryloxide; zirconium compounds such as zirconium acetate, zirconium oxide, zirconium alkoxide or aryloxide, zirconium acetylacetone And the like.

When catalysts are 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. The molten polymer of the present invention is a general term for an aromatic polycarbonate in a molten state and an aromatic polycarbonate prepolymer in a molten state. Here, the aromatic polycarbonate prepolymer is a polycondensate having a molecular weight lower than that of the final product aromatic polycarbonate in an intermediate stage when the aromatic polycarbonate of the present invention is produced from the aromatic dihydroxy compound and the diaryl carbonate. means.

The gradient according to the present invention is defined by defining the inclination of the pipe as a percentage of the vertical distance with respect to the horizontal distance.
Is a value shown as in equation (1) using the lengths a and b at Slope (%) = 100 × b / a (2) Here, the vertical distance b is a positive sign when facing downward, and a negative sign when facing upward. On the other hand, the horizontal distance a has a positive sign both when facing left and when facing right.

In the case where pipes having different slopes are combined with each other, the length, a ₁ ,
a ₂ , a ₃ ,... a _i and b ₁ , b ₂ , b _{3 ,.}
Is a value represented by the following equation (3).

[0037]

(Equation 1)

[0038] However, the vertical distance b _i is the sign of the downward Tokimasa, a negative sign when the upward. On the other hand, the horizontal distance a
_i has a positive sign both when facing left and when facing right.
In the present invention, down flow means that the fluid in the pipe has a gradient flowing downward, and up flow means that the fluid in the pipe has a gradient flowing upward. In addition, the horizontal pipe indicates a pipe in which the flow direction of the fluid is horizontal.

The transfer of the molten polymer is performed when the aromatic polycarbonate prepolymer is transferred from one polymerization vessel to the next polymerization vessel, when the aromatic polycarbonate is withdrawn from the polymerization vessel, and when the polymerized aromatic polycarbonate is in a molten state. This is necessary when transferring to a polymer mixer, extruder, or the like. In the present invention, when the number average molecular weight of these molten polymers is 4000 or more, it is necessary that the piping for transferring the molten polymers has a downflow with an average gradient of 1% or more. If the average gradient of the pipe for transferring the molten polymer having a number average molecular weight of 4000 or more is not downflow of 1% or more, it is impossible to sufficiently reduce the fine foreign matter in the polycarbonate product.
The average gradient of the pipe for transferring the molten polymer having a number average molecular weight of 4000 or more is more preferably 2% or more downflow, and even more preferably 5% or more downflow. Further, in a pipe for transferring a molten polymer having a number average molecular weight of 4000 or more, the length of a downflow pipe with a gradient of 1% or more (A), the length of a downflow pipe with a gradient of less than 1% (B), and the length of a horizontal pipe (C) and the length (D) of the upflow pipe must satisfy the following equation (1): A / (A + B + C + D)> 0.9 (1) Even if the intermediate system is not satisfied, it is not possible to sufficiently reduce the minute foreign matter in the aromatic polycarbonate product. Particularly preferred is a case where all pipes for transferring a molten polymer having a number average molecular weight of 4000 or more are downflows in the vertical direction. It is not clear why the method of the present invention can reduce the fine foreign matter in the aromatic polycarbonate, but the fine foreign matter of 1 μm or less has a number average molecular weight of 400.
It is considered that the molten polymer is easily generated in a pipe for transporting a molten polymer of 0 or more, and particularly, the molten polymer is easily generated in a horizontal pipe or the like in which the local polymer tends to stay locally for a long period of time.

In the present invention, the total distance of the piping for transferring the molten polymer having a number average molecular weight of 4000 or more is 1
It is preferably 5 m or less, more preferably 10 m or less. In the present invention, it is preferable that foreign substances of 1 μm or less present in the aromatic polycarbonate prepolymer having a reaction rate of the aromatic dihydroxy compound of 5 to 90% are removed by a filter. More preferably, foreign substances of 1 μm or less present in an aromatic polycarbonate prepolymer having a reaction rate of an aromatic dihydroxy compound of 10 to 80%, particularly preferably 20 to 75%, are removed. From the weight (E) of the aromatic dihydroxy compound used as a raw material and the weight (F) of the unreacted aromatic dihydroxy compound in the aromatic polycarbonate prepolymer, the reaction rate of the aromatic dihydroxy compound is represented by the following formula (3). It is calculated from:

Reaction rate (%) of aromatic dihydroxy compound = 100 × ( E− F) / E (3) An aromatic polycarbonate prepolymer having a reaction rate of aromatic dihydroxy compound of 5 to 90% has a low melt viscosity. Therefore, pressure rise due to filter clogging and the like hardly occurs, and minute foreign matters of 1 μm or less can be easily removed. In the case of an aromatic polycarbonate prepolymer in which the conversion of the aromatic dihydroxy compound is lower than 5%, the undissolved aromatic dihydroxy compound is often removed by a filter, which is not preferable. In the case of an aromatic polycarbonate prepolymer in which the reaction rate of an aromatic dihydroxy compound is higher than 90%, when a filter is used to remove minute foreign substances of 1 μm or less due to high melt viscosity,
Pressure rises easily.

It is preferable to use a filter having an absolute filtration accuracy of 0.1 to 0.5 μm as a filter for removing minute foreign substances of 1 μm or less. Absolute filtration accuracy 1-10μ
It is also a preferable method to combine an m filter and a filter of 0.1 to 0.5 μm to remove relatively large foreign matter and then remove minute foreign matter of 1 μm or less. An example of a preferred embodiment of the present invention will be described with reference to the drawings.

In FIG. 3, an aromatic dihydroxy compound and a diaryl carbonate are introduced into a stirred tank type polymerization vessel 3 and a stirred tank type polymerization vessel 3 'through raw material supply ports 1, 1'. The stirred tank type polymerization vessel 3 'is exactly the same as the stirred tank type polymerization vessel 3, and can be switched and used when operating in batch mode. The inside of the polymerization vessel is under an atmosphere of an inert gas such as nitrogen, which is usually controlled at around normal pressure, and the aromatic monohydroxy compound to be distilled is discharged from the vent ports 2 and 2 '. The aromatic polycarbonate prepolymers 5, 5 'obtained by reacting for a predetermined time while stirring with the stirring shafts 4, 4' are discharged from outlets 6, 6 '. Aromatic polycarbonate prepolymer 5, 5 '
Has a dihydroxy compound conversion of 5 to 90% and a number average molecular weight of less than 4000. The aromatic polycarbonate prepolymers 5 and 5 ′ are fed through the transfer pipe 7, the transfer pump 8, and the filter 51 to remove foreign matter of 1 μm or less, and then transferred through the transfer pipe 9 to the supply port 11 of the perforated plate type polymerization vessel 10. It is further supplied to the circulation line 12, introduced into the interior through the perforated plate 13, and falls as a thread-like molten polymer 14. The pressure inside the polymerization vessel is controlled to a predetermined pressure. Distilled aromatic monohydroxy compound and the like, and inert gas such as nitrogen introduced from the gas supply port 15 as needed are discharged from the vent port 16. Is done. The molten polymer that has reached the bottom of the polymerization vessel is supplied again from the perforated plate 13 into the polymerization vessel through the circulation line 12 provided with the circulation pump 17. The aromatic polycarbonate prepolymer 18 having reached a predetermined molecular weight is discharged from a discharge port 20 by a transfer pump 19. The number average molecular weight of the aromatic polycarbonate prepolymer 18 is less than 4000.
The aromatic polycarbonate prepolymer 18 is supplied to the perforated plate type polymerization reactor 2 from the supply port 22 through the transfer pipe 21 through the supply port 22.
3, is introduced into the inside of the polymerization vessel through the perforated plate 24, and falls along the wire 25. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound distilled from the polymerization intermediate and an inert gas such as nitrogen introduced from the gas supply port 26 as needed are vented. It is discharged from the mouth 27. The aromatic polycarbonate prepolymer 28 is discharged from the discharge port 29, and is supplied to the perforated plate type polymerizer 34 with a wire from the supply port 33 through the transfer pipe 30, the transfer pump 31, and the transfer pipe 32. It is introduced into the inside of the polymerization vessel and falls along the wire 36. The number average molecular weight of the aromatic polycarbonate prepolymer 28 is 4000 or more. The inside of the polymerization vessel is controlled to a predetermined pressure, and an aromatic monohydroxy compound and the like distilled out of the polymerization intermediate and an inert gas such as nitrogen introduced from the gas supply port 37 as needed are vented. It is discharged from the port 38. The aromatic polycarbonate 39 is discharged from the discharge port 40, and is extracted from the extraction port 44 through the transfer pipe 41, the transfer pump 42, and the transfer pipe 43.

In the transfer pipes 30, 32, 41, and 43, the average gradient of the pipes is 1% or more, the length (A) of the downflow pipe having a gradient of 1% or more, and the length of the downflow pipe having a gradient of less than 1%. The relationship between the length (B), the length of the horizontal pipe (C), and the length of the upflow pipe (D) satisfies the following equation: 1 A / (A + B + C + D)> 0.9 (1) Most preferred is piping 30,
32, 41, and 43 are all vertically downward.

Each polymerization reactor, circulation line, transfer line, discharge line and the like are all heated and kept warm by a jacket or a heater. Further, a case where an extruder or the like for adding and kneading a stabilizer is connected to the outlet 44 is also a preferred embodiment of the present invention. It is also a preferable method to provide a polymer filter in the extruder in order to further reduce foreign matters.

The material of the piping for achieving the method of the present invention is not particularly limited, and is usually selected from stainless steel, nickel, glass lining and the like. The shape and diameter of the pipe are not particularly limited, but preferably have a structure in which the molten polymer does not locally stay.

[0047]

Embodiments of the present invention will be described below in detail. The molecular weight is a number average molecular weight (hereinafter abbreviated as Mn) measured by gel permeation chromatography (GPC). The color is CIELA
Measured at 3.2 mm test specimen thickness by Method B,
^* Indicated by value. The amount of the minute foreign matter in the range of 0.5 μm to 1.0 μm was measured by a foreign matter measuring instrument manufactured by Hiac Leuco. The reaction rate of the aromatic dihydroxy compound in the aromatic polycarbonate prepolymer was determined by measuring the concentration of the aromatic dihydroxy compound in the prepolymer by high performance liquid chromatography.

[0048]

Example 1 An aromatic polycarbonate was produced by a process as shown in FIG. The stirred tank type polymerization units 3 and 3 'were operated in batches while switching, and the other polymerization units were continuously operated. The stirring tank type polymerization vessels 3 and 3 'are provided with anchor type stirring blades. The porous plate type polymerization vessel 10 has a pore size of 7
It has a perforated plate having 50 mm holes, and the distance from the perforated plate to the liquid reservoir below the polymerization vessel is 8 m. Perforated plate type polymerizer with wire 23 and perforated plate type polymerizer with wire 34
Are equipped with a perforated plate having 50 holes each having a hole diameter of 5 mm. 1mm diameter SUS316 vertically from the center of the hole
A wire made of the polymer was hung down to the liquid reservoir at the lower part of the polymerization vessel.

The stirring tank type polymerization reactors 3 and 3 'are all under the conditions of a reaction temperature of 180 ° C., a reaction pressure of normal pressure, and a flow rate of 1 L / hr of nitrogen gas for sealing. 80 Kg of bisphenol A and diphenyl carbonate (molar ratio to bisphenol A 1.10) were charged to the first polymerization vessel 3 of the stirring tank 4 and melt-mixed for 4 hours, and the molten aromatic polycarbonate prepolymer was continuously mixed at 10 liter / hr into a porous plate type. It was supplied to the polymerization vessel 10. While the mixture is being supplied from the stirred tank type polymerization apparatus 3 to the perforated plate type polymerization apparatus 10, bisphenol A and diphenyl carbonate are melt-mixed in the stirred tank type polymerization apparatus 3 'in the same manner as in the stirred tank type polymerization apparatus 3, and the mixture is stirred. When the tank type polymerization vessel 3 became empty, it was switched to the stirred tank type polymerization vessel 3 '. Thereafter, the aromatic polycarbonate prepolymer is continuously fed into the perforated plate type polymerizer 10 through the transfer pump 8 and the filter 51 while switching the batch type first polymerizers 3 and 3 ′ in the same manner. The feed was continued at liter / hr. The supplied aromatic polycarbonate prepolymer has a bisphenol A conversion of 73%. The filter 51 is a combination of a filter having an absolute filtration accuracy of 5 μm and a filter having an absolute filtration accuracy of 0.3 μm. The perforated-plate type polymerization vessel 10 has a reaction temperature of 235 ° C., a reaction pressure of 10 mmHg, and a circulation flow
When the liquid volume in the lower reservoir of the polymerization reactor reached 20 liters, the aromatic polycarbonate prepolymer was continuously supplied to the perforated plate type polymerization reactor 23 with a wire so as to keep the liquid volume constant at 20 liters. Supplied. The perforated-plate type polymerization reactor with wire 23 is operated under the conditions of a reaction temperature of 250 ° C., a reaction pressure of 1 mmHg, and a nitrogen gas flow rate of 2 liter / hr. The aromatic polycarbonate prepolymer was continuously supplied to the perforated plate type polymerization reactor 34 with a wire so as to keep a constant. In the perforated-plate type polymerization reactor 34 with a wire, the reaction temperature is 260 ° C. and the reaction pressure is 0.4 mmHg. When the liquid volume of the lower reservoir of the polymerization reactor reaches 20 liters, the liquid volume is kept constant at 20 liters. Aromatic polycarbonate was extracted from the extraction port 44. The transfer pipes 30, 32, 41, and 43 were all pipes directed downward in the vertical direction, and the total distance was 4 m.

After 300 hours from the start of the operation, the aromatic polycarbonate prepolymer discharged from the perforated-plate type polymerizer 10 and the perforated-plate type polymerizer with wire 23 and the aromatic discharged from the perforated-plate type polymerizer with wire 44 Mn of the polycarbonate was 2,100, 5900, and 10100, respectively. Further, after 300 hours, the perforated plate type polymerization reactor with wire 44
The color b ^* value of the aromatic polycarbonate discharged from the above was as good as 3.3, and the amount of minute foreign matters in the range of 0.5 μm to 1.0 μm was as small as 630 / g. Also, even after 1000 hours from the start of operation, no increase in the discharge pressure of the transfer pump 8 due to clogging of the filter 51 was observed.

[0051]

Examples 2 to 7 An aromatic polycarbonate was produced in exactly the same manner as in Example 1 except that the gradient of the transfer pipes 30, 32, 41 and 43 was changed. 300 hours after the start of operation,
The molecular weight at the outlet of each polymerization vessel was the same as in Example 1. 3
After 00 hours, the color b ^* value of the aromatic polycarbonate discharged from the perforated plate polymerization unit 44 with a wire, and 0.5
Table 1 summarizes the amount of minute foreign matter in the range of μm to 1.0 μm.

[0052]

Comparative Examples 1 to 3 An aromatic polycarbonate was produced in exactly the same manner as in Example 1 except that the gradient of the transfer pipes 30, 32, 41 and 43 was changed. 300 hours after the start of operation,
The molecular weight at the outlet of each polymerization vessel was the same as in Example 1. 3
After 00 hours, the color b ^* value of the aromatic polycarbonate discharged from the perforated plate polymerization unit 44 with a wire, and 0.5
Table 1 summarizes the amount of minute foreign matter in the range of μm to 1.0 μm.

[0053]

Example 8 An aromatic polycarbonate was produced by a process as shown in FIG. The process of FIG. 4 is exactly the same as that of FIG. 3 except that a horizontal twin-screw polymerization reactor 46 is used instead of the perforated-plate polymerization reactor 23 with a wire in FIG. The polymerization reactors other than the horizontal twin-screw polymerization reactor 46 were operated under the same reaction conditions as in Example 1. The horizontal twin-screw polymerization reactor has a double-screw stirring blade with L / D = 6 and a rotating diameter of 140 mm, a reaction temperature of 265 ° C. and a reaction pressure of 0.8 m.
Under conditions of mHg, the aromatic polycarbonate prepolymer was transferred to a perforated plate type polymerization reactor with a wire so that the liquid volume in the polymerization reactor was kept constant at 10 liters. Transfer piping 4
9, 32, 41 and 43 are all vertically downward pipes, and the total distance is 3 m. 300 hours after the start of the operation, the perforated plate type polymerization vessel 10 and the horizontal twin-screw polymerization type polymerization vessel 46
Mn of the aromatic polycarbonate prepolymer discharged from the above and the aromatic polycarbonate discharged from the perforated plate type polymerization reactor with wire 44 are 2100, 5200,
9,500. Further, the color b ^* value of the aromatic polycarbonate discharged from the perforated plate type polymerization reactor 44 with wire after 300 hours is as good as 3.4, and the amount of fine foreign matters in the range of 0.5 μm to 1.0 μm is as follows. 840 / g.

[0054]

Example 9 The operation was carried out under the same reaction conditions as in Example 1 except that the reaction pressure in the perforated plate type polymerization reactor 23 with a wire was set to 2.5 mmHg. The transfer pipes 41 and 43 are downflow pipes that face downward in the vertical direction, and have a length of 1.5 m. The transfer pipes 30, 32, 41, and 43 are down-flow pipes having an average gradient of 0.5% and have a length of 3.5 m. Transfer piping 3
0, 32, 41 and 43, the length (A) of the downflow pipe with a slope of 1% or more, the length of the downflow pipe with a slope of less than 1% (B), and the length of the horizontal pipe (C) ), The relationship of the length (D) of the upflow pipe is A / (A + B + C + D) = 0.8.

Further, 300 hours after the start of the operation, the aromatic polycarbonate prepolymer discharged from the perforated-plate type polymerization vessel 10 and the perforated-plate type polymerization apparatus 23 with the wire, and discharged from the perforated-plate type polymerization apparatus 44 with the wire. Mn of the aromatic polycarbonate was 2,100, 3800, and 7900, respectively. After 300 hours, the color b ^* value of the aromatic polycarbonate discharged from the perforated plate type polymerization reactor 44 with a wire is good at 3.3, and the amount of minute foreign matters in the range of 0.5 μm to 1.0 μm is 610. Pcs / g. That is, the transfer pipes 30, 32, 41, and 43 are down-flow pipes with an average gradient of 0.5%, and A / (A + B + C
+ D) = 0.8, but in the case of the present embodiment in which the Mn of the aromatic polycarbonate prepolymer in the transfer pipes 30 and 32 was 3800, the amount of fine foreign matters did not increase.

[0056]

Example 10 An aromatic polycarbonate was produced in exactly the same manner as in Example 1 except that the filter 51 was not used.
The molecular weight at the outlet of each polymerization reactor 300 hours after the start of the operation was the same as in Example 1. After 300 hours, the color b ^* value of the aromatic polycarbonate discharged from the perforated plate type polymerization reactor with wire 44 was as good as 3.3 and 0.5 μm.
3500 particles / g of fine foreign matter in the range of m to 1.0 μm
Met.

[0057]

[Table 1]

[0058]

As described above, it is possible to produce a high-quality aromatic polycarbonate with little coloring and little fine foreign matter without increasing the load on the extruder and without causing the problem of filter clogging.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a gradient of a pipe according to the present invention.

FIG. 2 is a diagram illustrating an average gradient of a pipe according to the present invention.

FIG. 3 is a schematic view showing an example of the process of the present invention.

FIG. 4 is a schematic view showing an example of the process of the present invention.

[Explanation of symbols]

1, 1 'raw material supply port 2, 2', 16, 27, 38, 47 vent port 3, 3 'stirring tank type polymerizer 4, 4' stirring shaft 5, 5 ', 18, 28 aromatic polycarbonate prepolymer 6 , 6 ', 20, 29, 40, 48 Outlets 7, 9, 21, 30, 32, 41, 43, 44, 49
Transfer piping 8, 19, 31, 42, 50 Transfer pump 10 Perforated plate type polymerizer 11, 22, 33, 45 Supply port 12 Circulation line 13, 24, 35 Perforated plate 14 Threaded molten polymer 15, 26, 37 Gas supply Port 17 Circulating pump 23, 34 Perforated plate type polymerization device with wire 25, 36 Wire 39 Aromatic polycarbonate 44 Extraction port 46 Horizontal twin-screw type polymerization device

Claims (3)

[Claims] 1. An aromatic dihydroxy compound and a diaryl carbonate, using one or two or more polymerization vessels,
In producing an aromatic polycarbonate by polymerization in a molten state, a pipe for transferring a molten polymer having a number average molecular weight of 4000 or more has an average gradient of 1 pipe.
% Of downflow pipe with slope of 1% or more and slope of 1% or more (A), length of downflow pipe with slope of less than 1% (B), length of horizontal pipe (C), upflow A method for producing an aromatic polycarbonate, characterized in that the relationship of the length (D) of the pipe satisfies the following formula: 1 A / (A + B + C + D)> 0.9 (1) 2. The process for producing an aromatic polycarbonate according to claim 1, wherein the total distance of a pipe for transferring a molten polymer having a number average molecular weight of 4000 or more is 15 m or less. 3. An aromatic dihydroxy compound and a diaryl carbonate, using one or two or more polymerization vessels,
When producing an aromatic polycarbonate by polymerizing in a molten state, foreign matter of 1 μm or less present in an aromatic polycarbonate prepolymer having a reaction rate of an aromatic dihydroxy compound of 5 to 90% is removed by a filter, and In a pipe for transferring a molten polymer having an average molecular weight of 4000 or more, the downflow of the pipe has an average gradient of 1% or more, and the length (A) of the downflow pipe having a gradient of 1% or more and the gradient of 1% The relationship between the length of the downflow pipe (B), the length of the horizontal pipe (C), and the length of the upflow pipe (D) is less than the following equation 1 A / (A + B + C + D)> 0.9 (1) A method for producing an aromatic polycarbonate, characterized by satisfying the following.