JP2003034721A - Production method for aromatic polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aromatic polycarbonate having no change in a terminal group ratio of polycarbonate after starting the production and having no discoloring, by using a stainless steel-made reactor. SOLUTION: A stainless steel-made reactor is rinsed with a solution containing a basic compound in a specific concentration and an aromatic hydroxy compound and then, the aromatic dihydroxy compound and diaryl carbonate are reacted to obtain the aromatic polycarbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-quality aromatic polycarbonate with little loss during production and without coloring.

[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 been conducted on the production method of the aromatic polycarbonate, and among them, aromatic dihydroxy compounds such as 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 hydrogen chloride and sodium chloride produced as by-products and chlorine-containing compounds such as methylene chloride used in large amounts as a solvent corrode the apparatus. However, there is a problem that impurities such as sodium chloride, which adversely affect the physical properties of the polymer, and separation of residual methylene chloride are difficult. On the other hand, as a method for producing an aromatic polycarbonate from an aromatic dihydroxy compound and a diaryl carbonate, for example, a melting method of transesterifying bisphenol A and diphenyl carbonate in a molten state has been known. Unlike the interfacial polycondensation method, the melting method has advantages such as not using a solvent, but since the reaction must be carried out under high temperature and high vacuum, there is a problem that the produced polycarbonate is easily colored.

It has been pointed out that this coloring in the melting method is closely related to the material used for the reactor, and it has been known that the coloring cannot be escaped when a stainless steel reactor is used. . For example, USP-
No. 4,383,092 proposes to use tantalum, nickel or chromium as a reactor material in order to prevent this coloring. In addition, Japanese Patent Laid-Open No. 4-723
No. 27 and JP-A-4-88017 propose a reactor material containing 85% by weight or more of chromium or nickel and a reactor material containing 20% by weight or less of iron, respectively. However, all of these materials are not practical because they are expensive and difficult to construct.

On the other hand, a method of using inexpensive stainless steel as a reactor material has also been proposed (JP-A-4-73).
28, JP-A-4-7329). In these methods, a method of buffing stainless steel or pickling it is proposed in order to prevent coloring of the aromatic polycarbonate. However, buffing and pickling
It is a treatment that is usually carried out when stainless steel is used, and it is not possible to sufficiently prevent product coloring with a stainless steel reactor by such a treatment, as described in the above-mentioned USP-4383092. It is also clear from.

In view of the above technical situation, the present inventors have
It was found and proposed that a colorless polycarbonate can be obtained by washing a stainless steel reactor with a liquid containing an aromatic hydroxy compound (JP-A-6-56984). By this method, the hue of the aromatic polycarbonate obtained was significantly improved. However, subsequent studies have revealed that with this method, the terminal group ratio of the aromatic polycarbonate obtained at the start of production immediately after washing tends to fluctuate and production loss tends to occur.

[0007]

DISCLOSURE OF THE INVENTION The present invention uses a reactor made of an inexpensive material when producing an aromatic polycarbonate by a melting method, and in particular, a stainless steel reactor which can be easily formed into various shapes and is easy to construct. It was made to find a method for obtaining a product without color loss even when the above is used.

[0008]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that when a reactor is washed with a liquid containing an aromatic hydroxy compound, a specific amount of a basic compound is used. It has been found that the purpose can be easily achieved by incorporating the compound, and the present invention has been completed. That is, according to the present invention, (1) in reacting an aromatic dihydroxy compound with a diaryl carbonate to produce an aromatic polycarbonate, the basic compound 1 to
Iron content of the wetted part containing 10000 ppb and washed with a liquid containing an aromatic hydroxy compound is 20%
A method for producing an aromatic polycarbonate characterized by using a reactor made of the above materials, (2) The material of the reactor is stainless steel, above (1)
The method for producing an aromatic polycarbonate described above, (3) The method for producing an aromatic polycarbonate described in (1) or (2) above, wherein the basic compound is an alkali metal compound, and (4) the aromatic hydroxy compound is phenol. The method for producing an aromatic polycarbonate described in (1) to (3) above is provided.

It is generally well known that when an aromatic hydroxy compound such as phenol or a basic compound is present in the aromatic polycarbonate, these aromatic polycarbonates are easily colored when heated and melted. It is also well known that deactivation of the stainless steel surface is generally carried out by washing with an acid or heat treatment. Under such circumstances, a liquid containing an aromatic hydroxy compound such as phenol and a basic compound has an excellent effect of cleaning a reactor made of a material containing 20% or more of iron, and an aromatic compound at the start of production immediately after the cleaning. The fact that a variation in the end group ratio of the polycarbonate is suppressed and an aromatic polycarbonate having no coloration is obtained has heretofore been completely unexpected. Among them, although the mechanism by which the basic compound stabilizes the terminal ratio of the polycarbonate is unknown, there are some active sites that affect the polycondensation reaction of the aromatic polycarbonate on the surface of the reactor steel, and the active sites are sealed. It is presumed that it has stopped. In any case, the effect was totally unexpected.

The present invention will be described in detail below. In the present invention, the aromatic dihydroxy compound means 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 Y, 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 are other substituents that do not adversely affect the reaction, for example, a halogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms. 10 alkoxy groups, phenyl groups, phenoxy groups, vinyl groups, cyano groups, ester groups,
It may be substituted with an amide group, a nitro group or the like.

Preferred specific examples of the heterocyclic aromatic group include aromatic groups having one or more ring-forming nitrogen atoms, oxygen atoms 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 substituents here are as described above. The divalent alkane group Y is, for example, an organic group represented by the following chemical formula 1.

[0012]

[Chemical 1]

(In the formula, R ¹ , R ² , R ³ , and R ⁴ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms.
Of the above, a cycloalkyl group having 5 to 10 ring carbon atoms, a carbocyclic aromatic group having 5 to 10 ring carbon atoms, and a carbocyclic aralkyl group having 6 to 10 carbon atoms. k is 3 to 1
Represents an integer of 1, R ⁵ and R ⁶ are individually selected for each X and, independently of each other, represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and X represents carbon. In addition, R ¹ , R ² ,
In R ³ , R ⁴ , R ⁵ , and R ⁶ , other substituents such as a halogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms are used as long as one or more hydrogen atoms do not adversely affect the reaction. 1
It may be substituted with an alkoxy group of 0, 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 chemical formula 2.

[0014]

[Chemical 2]

(In the formula, 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, or a cycloalkyl group having 5 to 10 carbon atoms in the ring. 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 the case of, each R ⁸ may be the same or different. ) Furthermore, a divalent aromatic group Ar is, -Ar ¹ -Z-Ar ² -
It may be shown by. (In the formula, 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.
However, R ¹ is as described above. ) Examples of such a divalent aromatic group Ar include those represented by the following chemical formula 3.

[0016]

[Chemical 3]

(In the formula, 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 phenylene. Substituted naphthylene, substituted or unsubstituted pyridylene and the like can be mentioned. The aromatic dihydroxy compound used in the present invention may be a single type or two or more types. A typical example of the aromatic dihydroxy compound is bisphenol A. The diaryl carbonate used in the present invention is
It is represented by the following chemical formula 4.

[0018]

[Chemical 4]

(Where Ar is³, Ar^FourEach is a monovalent
Represents an aromatic group. ) Ar³And Ar^FourIs a monovalent carbocyclic or heterocyclic aromatic
Represents a group, but this Ar ³, Ar^FourIn one or more water
Other substituents whose elementary atom does not adversely affect the reaction, for example,
For example, halogen atom, alkyl group having 1 to 10 carbon atoms, carbon
Number 1-10 alkoxy group, phenyl group, phenoxy
Group, vinyl group, cyano group, ester group, amide group, nit
It may be substituted with a group such as b. Ar
³And Ar^FourCan be the same or different
You can

Typical 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 types of the above-mentioned substituents. Examples of preferable Ar ³ and Ar ⁴ include the following chemical formulas 5 and the like.

[0021]

[Chemical 5]

Representative examples of the diaryl carbonate include substituted or unsubstituted diphenyl carbonates represented by the following chemical formula 6.

[0023]

[Chemical 6]

(In the formula, R ⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms.
An alkoxy group having 10 or a cycloalkyl group having 5 to 10 ring carbon atoms or a phenyl group, and p and q are 1 to
When R is an integer of 5 and 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
Symmetrical diaryl carbonates, such as lower alkyl-substituted diphenyl carbonates such as -butylphenyl carbonate, are preferred, but unsubstituted diphenyl carbonates, which are the diaryl carbonates of the simplest structure, are particularly preferred. These diaryl carbonates may be used alone or in combination of two or more.

The usage ratio (charge ratio) of the aromatic dihydroxy compound and the diaryl carbonate differs depending on the kind of the aromatic dihydroxy compound and the diaryl carbonate used, the polymerization temperature and other polymerization conditions. The diaryl carbonate is the aromatic dihydroxy compound. It is usually 0.9 to 2.5 mol, and preferably 0.1 to 1 mol.
It is used in a proportion of 95 to 2.0 mol, more preferably 0.98 to 1.5 mol.

In the present invention, an aromatic polycarbonate can be produced by subjecting an aromatic dihydroxy compound and a diaryl carbonate to a melt polycondensation reaction. The number average molecular weight of the aromatic polycarbonate obtained by the method of the present invention is usually in the range of 5,000 to 100,000, preferably in the range of 5,000 to 30,000. The temperature for carrying out the melt polycondensation is usually 50 to 350 ° C., preferably 1
It is selected in the temperature range of 50 to 290 ° C. Aromatic monohydroxy compounds are produced as the reaction progresses, but the reaction rate can be increased by removing them from the reaction system. Therefore, an inert gas such as nitrogen, argon, helium, carbon dioxide, or a lower hydrocarbon gas that does not adversely affect the reaction is introduced, and the produced aromatic monohydroxy compound is removed together with these gases. And the method of carrying out the reaction under reduced pressure are preferably used. The preferred reaction pressure also depends on the molecular weight,
The range of 10 mmHg to normal pressure is preferable in the initial stage of polymerization, and 20 mmHg or less, particularly 10 mmHg or less is preferable and 2 mmHg or less is more preferable in the latter stage of polymerization.

As the polymerization reactor, 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,
A perforated plate reactor that polymerizes while free falling, a perforated plate reactor with a wire that polymerizes while falling along a wire, and the like are used, but even if these are used alone,
You may use it in combination. In the present invention, at least one of these polymerizers is made of a material whose liquid contact portion has an iron content of 20% or more. Among such materials, stainless steel is particularly preferably used. Stainless steel includes martensite-based, ferrite-based, austenite-based, ferrite, which usually contains 10 to 30% by weight of chromium as defined and classified in Stainless Steel Handbook, pages 13 to 21 (published by Nikkan Kogyo Shimbun, 5th edition). -Stainless steel such as austenitic stainless steel. As a specific example, SUS201, SUS2
02, SUS304, SUS304L, SUS316,
SUS316L, SUS347, SUS405, SUS
430, SUS403, SUS410, SUS431,
Examples thereof include SUS440C and SUS630, but are not limited thereto. As a preferred specific example, S
US304, SUS304L, SUS316, SUS3
16 L and the like, and particularly preferably SUS316L. Further, the surface of stainless steel may be one that has been subjected to passivation treatment, pickling or buffing.

The production method of the present invention is a production method in which one or at least one polymerization vessel is combined, and the reaction between the aromatic dihydroxy compound and the diaryl carbonate can be carried out batchwise or continuously. . In the present invention, the melt polycondensation reaction can be carried out without adding a catalyst, but 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 it is a hydroxide of an alkali metal or an alkaline earth metal such as lithium hydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide. 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 or alkaline earth metal hydrogen compounds such as calcium hydride; alkali metal or alkaline earth metal alkoxides such as lithium methoxide, sodium ethoxide, calcium methoxide; lithium phenoxide, sodium phenoxide, magnesium phenoxide Kishido, Li
O-Ar-OLi, NaO-Ar-ONa (Ar is an aryl group) and other alkali metal or alkaline earth metal aryloxides; lithium acetate, calcium acetate, sodium benzoate and other alkali metal or alkaline earth metal organics Acid salts; zinc compounds such as zinc oxide, zinc acetate, zinc phenoxide; boron oxide, boric acid, sodium borate, trimethyl borate, tributyl borate,
Triphenyl borate, ammonium borate represented by (R ¹ R ² R ³ R ⁴ ) NB (R ¹ R ² R ³ R ⁴ ), (R ¹ R ² R ³ R ⁴ ) PB (R ¹ R ²
R ³ R ⁴ ) represented by phosphonium borates (R ¹ , R ² ,
R ³ and R ⁴ are as described above in Chemical Formula 1. ) And other boron compounds; silicon compounds such as silicon oxide, sodium silicate, tetraalkyl silicon, tetraaryl silicon, and diphenyl-ethyl-ethoxy silicon; germanium oxide, germanium tetrachloride, germanium ethoxide, germanium phenoxide, etc. Germanium compounds; tin compounds such as tin oxide, dialkyltin oxide, dialkyltin carboxylate, tin acetate, ethyltin tributoxide, etc., bound with alkoxy groups or aryloxy groups, tin compounds such as organotin compounds; lead oxide Lead compounds such as lead acetate, lead carbonate, basic carbonate, lead and organic lead alkoxides or aryloxides; 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, manganese borate; titanium such as titanium oxide, titanium alkoxides or aryloxides. Examples thereof include zirconium acetate, zirconium oxide, zirconium alkoxides or aryloxides, zirconium compounds such as zirconium acetylacetone, and other catalysts.

When a catalyst is used, these catalysts may be used alone or in combination of two or more. The amount of these catalysts used is usually 10 ^-8 to 100 parts by weight of the aromatic dihydroxy compound as a raw material.
It is selected in the range of ¹ part by weight, preferably 10 ^-7 to 10 ^-1 part by weight. Next, a liquid containing a basic compound and an aromatic hydroxy compound for cleaning the reactor in the present invention will be described.

The aromatic hydroxy compound of the present invention means A
r^FourOH (in the formula, Ar^FourIs Ar ², Ar³Same as
Indicated). Preferred Ar^FourAs a concrete example of
Inscription 5, etc. are mentioned. Especially the simplest structure
Nols are preferred. Contains aromatic monohydroxy compounds
A liquid having 1% by weight of an aromatic monohydroxy compound
0 ppm to 100%, preferably 100 ppm to 100
%, More preferably 1000 ppm to 100%
It is a liquid. Low content of aromatic hydroxy compounds
Increase the time required to clean the reactor.
It

The basic compound which can be used in the present invention is not particularly limited as long as it shows basicity in a liquid containing an aromatic hydroxy compound, but the basic compound is generally heated with an aromatic polycarbonate. Then, since the aromatic polycarbonate is colored or the transfer reaction is promoted, in the present invention, a compound showing basicity is preferably used among the above-mentioned polymerization catalysts. Of these, alkali metal compounds are preferable, and sodium hydroxide and potassium hydroxide are particularly preferable. The concentration of the basic compound in the washing solution is in the range of 1 to 10000 ppb, preferably 10 to 5000 ppb, and particularly preferably 20 to 1000 ppb. Outside the above range, the terminal ratio of the polycarbonate obtained during the production of the aromatic polycarbonate after washing varies, which is not preferable.

In the liquid containing the aromatic hydroxy compound used in the present invention, the components other than the aromatic hydroxy compound and the basic compound are not particularly limited,
A component that is uniformly mixed with the aromatic hydroxy compound under the condition of the washing treatment is preferable. Specific examples thereof include the above-mentioned aromatic dihydroxy compounds and diaryl carbonates, and a mixture thereof. An oligomer or polymer obtained by condensing an aromatic dihydroxy compound and a diaryl carbonate under melting usually contains an aromatic hydroxy compound, which is a preferred specific example for carrying out the present invention.

In the present invention, the temperature at which the reactor is washed with the aromatic hydroxy compound is not particularly limited,
It is usually in the range of 20 to 300 ° C, preferably 100 to 250 ° C. Further, the time required for the cleaning treatment is not particularly limited and is usually several minutes to several hundred hours, preferably 1 to 100 hours, though it varies depending on the liquid to be cleaned, the cleaning temperature and the like. The pressure for cleaning treatment may be any of reduced pressure, normal pressure and increased pressure. The cleaning treatment of the present invention can be carried out in either a batch system or a continuous system. In the case of the batch method, the treatment is carried out once or twice or more.

In the present invention, after the cleaning process is completed,
If necessary, a post-washing step for removing the washing-finished solution from the reactor is performed. The washing liquid used in the post-washing step is not particularly limited, but preferable examples include reaction raw materials such as aromatic dihydroxy compounds, diaryl carbonates or mixtures thereof; oligomers obtained by condensing aromatic dihydroxy compounds and diaryl carbonates under melting. And polymers.

It is well known to those skilled in the art that the aromatic polycarbonate obtained by contact with oxygen in producing the aromatic polycarbonate by melt polycondensation is known to those skilled in the art. It is preferable to make contact with oxygen as much as possible during polycondensation.
Therefore, prior to the cleaning treatment of the present invention, sufficiently replacing the reactor with an inert gas to remove oxygen is an effective method for obtaining a colorless aromatic polycarbonate in a short cleaning treatment. is there. It is also a preferable method to degas the liquid containing the aromatic hydroxy compound under reduced pressure to reduce the oxygen concentration in the liquid. Further, it is also effective not to bring oxygen into contact with the inside of the reactor after the washing treatment and before the melt polycondensation, in order to obtain a polycarbonate without coloring.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. In addition,
The molecular weight of the obtained aromatic polycarbonate is the number average molecular weight (hereinafter abbreviated as Mn) measured by gel permeation chromatography (GPC). The phenol concentration in the washing liquid was measured by liquid chromatography.
The color of the obtained aromatic polycarbonate is CIEL
The thickness of the test piece was measured by the AB method at a thickness of 3.2 cm, and the yellowness index was represented by the b ^* value. The terminal group ratio of the obtained aromatic polycarbonate was measured using ¹ H-NMR.

[0037]

Example 1 An aromatic polycarbonate was produced by the process as shown in FIG. The raw material dissolving and mixing tanks 3a and 3b were alternately operated in a batch manner, and the storage tank 10 and thereafter were continuously operated. Raw material dissolution / mixing tanks 3a and 3b and stirring tank type polymerizer 1
Each of Nos. 7 and 26 is equipped with a stirring blade, and the material of the liquid contact portion is SUS316L. The material of the liquid contact portion of the storage tank 10 is also SUS316L. The horizontal biaxial stirring type polymerizer 35 is
It has a biaxial stirring blade of L / D = 6 and a rotating diameter of 140 mm, and the material of the liquid contact part is SUS304. The perforated plate type polymerizer 42 with a wire is equipped with a perforated plate 43 having 50 holes with a diameter of 5 mm, and the liquid contact part is made of SUS31
It is 6L. SUS31 with a diameter of 1 mm vertically from the center of the hole
The 6-L wire 44 is hung down to the liquid reservoir below the polymerization vessel, and the dropping height is 8 m. Transfer pipes 7, 13, 15, 24, 33, 4 connecting between the melt mixing tanks and the polymerization vessel
The material of the liquid contact parts of 0 and 50 is SUS316.

Degassed phenol containing 300 ppb of sodium hydroxide as a basic compound was charged into each of the mixing tanks, the polymerization vessel, and the storage tank in a substantially full solution, and the batchwise washing was performed at 150 ° C. for 2 hours three times. The pipe was cleaned by passing a cleaning liquid through the pipe when the phenol was extracted from each tank. Then, the residual phenol was removed under reduced pressure. The raw material dissolution / mixing tanks 3a and 3b have a reaction temperature of 180 ° C., a reaction pressure of normal pressure,
The condition is a seal nitrogen (oxygen concentration of 0.5 ppm) gas flow rate of 1 liter / hr. 40m in the raw material melting and mixing tank 3a
80 kg of bisphenol A powder and diphenyl carbonate powder (molar ratio of bisphenol A to 1.10) which was subjected to vacuum nitrogen substitution 5 times with mHg, and sodium hydroxide 7 mg
Was charged and melt mixed for 5 hours, and the entire melt mixture was transferred to the transfer storage tank 10 through the transfer pipe 7a. The molten mixture is a molten polymer having a number average molecular weight of 350 and a reaction rate of 82.
%Met. Similarly, the raw materials were similarly dissolved and mixed in the raw material dissolving and mixing tank 3b and transferred to the storage tank 10 before the molten polymer in the storage tank 10 was exhausted. The raw material dissolution / mixing tanks 3a and 3b alternately repeat the dissolution mixing and transfer. Storage tank 10 is at atmospheric pressure, 1
It is kept at 81 ° C. The molten polymer transferred to the storage tank 10 was continuously stirred at 10 kg / hr with the stirring tank type first polymerizer 1
7 was supplied.

The stirring tank type first polymerizer 17 has a reaction temperature of 23.
Under the conditions of 4 ° C. and reaction pressure of 98 mmHg, when the liquid volume of the molten polymer reaches 20 liters, a molten polymer having a number average molecular weight of 850 is placed in the stirring tank type second polymerizer 26 so as to keep the liquid volume of 20 liter constant. It was supplied continuously. The stirring tank type second polymerizer 26 has a reaction temperature of 250 ° C. and a reaction pressure of 6
When the liquid volume of the molten polymer reaches 20 liters under the condition of mmHg, the number average molecular weight of 2,500 is set in the horizontal biaxial stirring type polymerizer 35 so as to keep the liquid volume of 20 liters constant.
Was continuously fed. In the horizontal biaxial stirring type polymerization vessel 35, the reaction temperature is 275 ° C. and the reaction pressure is 0.4 mmH.
When the liquid volume of the molten polymer reached 10 liters under the condition of g, the molten polymer having a number average molecular weight of 6500 was supplied to the wire perforated plate type polymerizer 42 so as to keep the liquid volume of 10 liters constant.

In the perforated plate type polymerization vessel with wire 42, the reaction temperature is 263 ° C. and the reaction pressure is 0.4 mmHg. When the liquid volume of the molten polymer in the lower portion of the polymerization vessel reaches 20 liters, the liquid volume is kept at 20 liters. So that the transfer pipe 50
After that, the aromatic polycarbonate having a number average molecular weight of 10,000 was extracted from the extraction port 51. The end group ratio of the aromatic polycarbonate discharged from the product discharge port 51 is
The ratio of end groups of phenolic hydroxyl groups contained in all end groups is 21
It was mol% and remained stable immediately after the start of operation. After 10 hours from the start of operation, the color b ^* value of the aromatic polycarbonate discharged from the product discharge port 51 was as good as 3.0, and the ratio of the phenolic hydroxyl groups contained in all the terminal groups was 21 mol% and the number average. The molecular weight was 10100.

[0041]

[Comparative Example 1] The same procedure as in Example 1 was carried out except that degassing phenol was used to wash each mixing tank, polymerization vessel and storage tank. The ratio of end groups of phenolic hydroxyl groups contained in all the end groups of the aromatic polycarbonate discharged from the product discharge port 51 is 63 mol% immediately after the start of operation and 45% after 5 hours, 10
After the lapse of time, it fluctuated greatly to 53%, and after 50 hours, it became 21 mol%. The aromatic polycarbonate obtained during this period was discarded and became a loss. After 10 hours from the start of operation, the number average molecular weight of the aromatic polycarbonate discharged from the product discharge port 51 is 10100, and the color b ^* value is
It was as good as 3.0.

[0042]

Comparative Example 2 The procedure of Example 1 was repeated, except that the mixing tank, the polymerization vessel, and the storage tank were not washed. Product outlet 51
The ratio of end groups of phenolic hydroxyl groups contained in all the terminal groups discharged from the reactor fluctuated greatly to 66 mol% 1 hour after the start of operation, 50% after 5 hours and 58% after 10 hours, and became 21 mol% after 65 hours. . The aromatic polycarbonate obtained during this period was discarded and became a loss. Ten hours after the start of operation, the number average molecular weight of the aromatic polycarbonate discharged from the product discharge port 51 was 10,000, and the color b ^* value was 5.8, which was poor.

[0043]

Example 2 Bisphenol A, diphenyl carbonate (molar ratio 1/1) and potassium hydroxide 50 were added to each mixing tank.
After charging ppb and holding at 180 ° C for 4 hours, 180 ° C
Transferred to the storage tank and each polymerization vessel held at
It was held for each hour and finally extracted from the product discharge port 51. The extracted bisphenol A partially reacts with diphenyl carbonate, and the concentration of phenol in the liquid is 3
It was 5%. After repeating the same operation 5 times, the residual washing liquid was removed under reduced pressure, and then bisphenol A and diphenyl carbonate were polymerized in the same manner as in Example 1.

Regarding the terminal group ratio of the aromatic polycarbonate discharged from the product discharge port 51, the ratio of the terminal groups of the phenolic hydroxyl groups contained in all the terminal groups was 22 mol%, which was stable immediately after the start of the operation. 10 hours after the start of operation,
The color b ^* value of the aromatic polycarbonate discharged from the product discharge port 51 was as good as 2.9, and the ratio of phenolic hydroxyl groups in all the terminal groups was 22 mol% and the number average molecular weight was 10,000.

[0045]

Example 3 An aromatic polycarbonate was produced in the same manner as in Example 1 except that o-cresol was used instead of phenol. Regarding the terminal group ratio of the aromatic polycarbonate discharged from the product discharge port 51, the ratio of the terminal groups of phenolic hydroxyl groups contained in all the terminal groups was 20 mol%, and it remained stable immediately after the start of operation. After 10 hours from the start of operation, the color b ^* value of the aromatic polycarbonate discharged from the product discharge port 51 was as good as 3.0, and the ratio of the phenolic hydroxyl group end groups in all the terminal groups was 20 mol%.
The number average molecular weight was 10200.

[0046]

Example 4 An aromatic polycarbonate was produced in the same manner as in Example 1 except that 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane was used instead of bisphenol A. Product outlet 51
Regarding the terminal group ratio of the aromatic polycarbonate discharged from, the terminal ratio of the phenolic hydroxyl group contained in all the terminal groups was 25 mol%, and it remained stable immediately after the start of the operation. After 10 hours from the start of operation, the color b ^* value of the aromatic polycarbonate discharged from the product discharge port 51 is 3.
The ratio was as good as 2, the phenolic hydroxyl group terminal ratio in all the terminal groups was 25 mol%, and the number average molecular weight was 9,500.

[0047]

Comparative Example 3 The procedure of Example 1 was repeated except that the concentration of sodium hydroxide was 0.8 ppb. Product outlet 5
The ratio of end groups of phenolic hydroxyl groups contained in all the end groups discharged from 1 greatly fluctuates to 65% after 1 hour from the start of operation, 48% after 5 hours and 59% after 10 hours.
It reached 21 mol% after time. The aromatic polycarbonate obtained during this period was discarded and became a loss. Ten hours after the start of operation, the number average molecular weight of the aromatic polycarbonate discharged from the product discharge port 51 was 10100, and the color b ^* value was 5.9, which was poor.

[0048]

Comparative Example 4 The procedure of Example 1 was repeated except that the concentration of sodium hydroxide was changed to 20 ppm. Product outlet 51
The ratio of the end groups of phenolic hydroxyl groups contained in all the terminal groups discharged from the reactor fluctuated greatly to 13% after 1 hour, 12% after 5 hours, 15% after 10 hours, and 22% after 82 hours. . The aromatic polycarbonate obtained during this period was discarded and became a loss. Ten hours after the start of operation, the number average molecular weight of the aromatic polycarbonate discharged from the product discharge port 51 was 10,000, and the color b ^* value was 4.9, which was poor.

[0049]

Industrial Applicability According to the present invention, it is possible to produce an aromatic polycarbonate with little loss during production and without coloring, by using a stainless steel reactor which is easy to construct.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of the process of the present invention.

[Explanation of symbols]

1a, 1b Raw material supply ports 2a, 2b, 9, 19, 28, 36, 46 Vent ports 3a, 3b Raw material dissolving and mixing tanks 4a, 4b, 18, 27, 39 Stirring shafts 5a, 5b, 11, 20, 29, 47 Molten polymer 6a. 6b, 12, 21, 30, 37, 48 Discharge ports 7a, 7b, 13, 15, 24, 33, 40, 50 Transfer pipes 8, 16, 25, 34, 41 Supply port 10 Storage tanks 14, 23, 32, 38 , 49 Transfer pump 17 Stirring tank type first polymerizer 22, 31, 45 Gas supply port 26 Stirring tank type second polymerizer 35 Horizontal biaxial stirring type polymerizer 42 Perforated plate type polymerizer with wire 43 Perforated plate 44 Wire 51 Product outlet

Continued front page    F term (reference) 4J029 AA10 AB04 BB11A BB12A                       BB13A BE05A BE07 BF14A                       BH01 BH02 DA10 DB07 DB11                       DB13 HC05A KD17 KJ06                       LA01 LA02

Claims (4)

[Claims] 1. When an aromatic polycarbonate is produced by reacting an aromatic dihydroxy compound with a diaryl carbonate, the aromatic polycarbonate is washed with a liquid containing 1 to 10000 ppb of a basic compound and containing an aromatic hydroxy compound. A process for producing an aromatic polycarbonate, characterized in that a reactor whose liquid contact portion is made of a material having an iron content of 20% or more is used. 2. The method for producing an aromatic polycarbonate according to claim 1, wherein the material of the reactor is stainless steel. 3. The method for producing an aromatic polycarbonate according to claim 1 or 2, wherein the basic compound is an alkali metal compound. 4. The method for producing an aromatic polycarbonate according to claim 1, wherein the aromatic hydroxy compound is phenol.