JPH06345860A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To produce a straight-chain polycarbonate having high molecular weight and excellent heat-resistance, hydrolysis resistance, hue and impact resistance using a production facility available at a low cost compared with conventional facility. CONSTITUTION:This polycarbonate is produced by the melt polycondensation of a bivalent hydroxy compound with a carbonic acid diester in the presence of an ester interchange catalyst. In this process, the Fe content of the material contacting with the reaction mixture is <=20wt.% in the 1st polycondensation reaction process and >20wt.% in the 2nd polycondensation reaction process and thereafter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polycondensing a divalent hydroxy compound and a carbonic acid diester in the presence of a transesterification catalyst to produce a high molecular weight polycarbonate without coloring.

[0002]

BACKGROUND OF THE INVENTION High molecular weight polycarbonates are versatile engineering thermoplastics having a wide range of applications, especially for injection molding or as glass sheets as an alternative to window glass. Polycarbonate is generally said to be excellent in heat resistance, transparency and impact resistance.

As a method for producing a polycarbonate, a phosgene method in which a divalent hydroxy compound and phosgene are subjected to interfacial polycondensation to react, or a transesterification method in which a divalent hydroxy compound and a carbonic acid diester are reacted in a molten state are generally known. ing.

As a typical example of the transesterification method, an ester exchange catalyst is added to a dihydric phenol and a carbonic acid diester to synthesize a prepolymer while distilling phenol under heating and reduced pressure, and finally under high vacuum. A method of obtaining a high-molecular-weight polycarbonate by heating above 290 ° C. to distill phenol (US Pat. No. 4345062) can be mentioned.

In the transesterification method, in order to allow the reaction to proceed efficiently, the prepolymer is synthesized in a tank reactor having an ordinary stirring blade in the initial stage of the reaction, and then an apparatus such as a vented horizontal extruder is used. It is known to carry out a polycondensation reaction to produce a high molecular weight polycarbonate.

However, unlike other engineering plastics, high molecular weight polycarbonate has a very high melt viscosity, and therefore requires a high temperature of 280 ° C. or higher as a reaction condition and distills off a monovalent hydroxy compound having a high boiling point. Since it requires a high vacuum (1-10 ^-2 torr), industrialization is difficult from the viewpoint of equipment, and it is not preferable for the hue, heat resistance, molding retention stability, water resistance and weather resistance of the polycarbonate produced. There was a problem that it affected.

Regarding the coloring of the resin, the influence of the material of the reactor has been clarified, and if the material that comes into contact with the reaction solution is a stainless steel-based material, the coloring of the resin can be seen. It is disclosed in patents such as 55-142025. In order to eliminate the influence of the material of the reactor, JP-A-2-153923 discloses that glass, nickel, tantalum, chromium, and Teflon should account for at least 90% or more of the total surface area of the liquid contact portion between the material and the reaction liquid. It is described that it is preferable to be composed of one kind or two or more kinds of them. Further, JP-A-4-72327 describes that the material of the liquid contact portion is preferably made of a metal or an alloy having a copper and / or nickel content of 85% by weight or more. Further, the present inventors have disclosed the usefulness of a material having a Fe content of 20% by weight or less in JP-A-4-88017. However, in these methods, although it is effective in eliminating the coloring of the resin, it is necessary to use a substantially expensive material, or when using a device having a complicated shape However, using special materials is often difficult in terms of workability and availability, and the cost of the device rises, which ultimately leads to an increase in product cost. . For these reasons, the advent of a more inexpensive polycarbonate production method has been strongly desired.

[0008]

As a result of investigating the cause of coloration of a resin in which a metal material is involved, the inventors of the present invention show remarkable coloration in a mixed system of three kinds of metal-polymerization catalyst-monovalent hydroxy compound. I found out. Here, the monovalent hydroxy compound is a by-product in the transesterification reaction between the divalent hydroxy compound and the carbonic acid diester. Then, as a result of conducting an experiment using some metals in the combination of these three kinds, the case where iron was used showed the most remarkable coloring. However, it has been found that, even if one of these three combinations is lacking, the degree of coloration is unlikely to be remarkable, and based on these findings, materials with a high iron content in the latter stage of the polymerization reaction are found. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, when a polycarbonate is produced by melt polycondensation of a divalent hydroxy compound and a carbonic acid diester in the presence of a transesterification catalyst,
In the first polycondensation reaction step, the material that comes into contact with the reaction mixture is
It relates to a method for producing a polycarbonate, which has an Fe content of 20% by weight or less and an Fe content of more than 20% by weight in the second polycondensation reaction step.

That is, at the initial stage of the polymerization in which a large amount of monovalent hydroxy compound is present in the reaction mixture, it is necessary to use a material having a low iron content as the material of the liquid contact part. Since the divalent hydroxy compound is distilled off under reduced pressure to the outside of the system, the amount of monovalent hydroxy compound in the reaction mixture is reduced in the latter stage of the polymerization, and therefore, even if a material having a high iron content is used, the resin is not colored. is there. In particular, since it is necessary to stir the highly viscous resin in the latter half of the polymerization, a reactor with a complicated shape is generally used, but since the material with a high iron content can be used, the equipment cost and eventually the product cost can be reduced. sell.

Next, the method for producing the polycarbonate according to the present invention will be described in detail. First, the first polycondensation reaction step is a step of carrying out an initial reaction of polymerization in the case of producing a polycarbonate by melt polycondensation of a divalent hydroxy compound and a carbonic acid diester in the presence of an ester exchange catalyst. The intrinsic viscosity [η] of the polymer obtained in this step is 0.1 to 0.4 dl / g. Here, the intrinsic viscosity [η] is 0.5% methylene chloride solution of the polymer,
It was measured using an Ubbelohde viscometer at 20 ° C. Further, the concentration of monohydric phenol in the polymer obtained in this step may be 10 ppm or more.

The second polycondensation reaction step is a step of carrying out the latter stage reaction of the polymerization in which the transesterification reaction is subsequently carried out after the first polycondensation reaction step, and the polymer finally obtained in this step. Has an intrinsic viscosity [η] of 0.3 to 1.0 dl / g
Is. Further, the concentration of monohydric phenol in the polymer obtained in the second polycondensation reaction step needs to be 10,000 ppm or less. This concentration is preferably 1,000 ppm or less, more preferably 100 ppm or less.
When the monohydric phenol is present in the polymer in an amount of 10,000 ppm or more, the polymer is markedly colored.

The first polycondensation reaction step and the second polycondensation reaction step may each be composed of a plurality of reactors and pipes.

In the present invention, in the first polycondensation reaction step, the material of at least the portion of the reaction apparatus for carrying out the transesterification reaction which is substantially in contact with the reaction mixture is Fe
It should be 20 wt% or less, preferably Fe content of 10 wt% or less. Specific examples of such materials include Hastelloy B (64% by weight of nickel, 1% by weight of chromium, molybdenum).
28% by weight, iron 5% by weight), Hastelloy C-276 (nickel
59% by weight, chromium 15.5% by weight, molybdenum 16% by weight, iron
5.5 wt%), Hastelloy G-30 (43 wt% nickel,
Molybdenum 7% by weight, iron 20% by weight, chromium 22% by weight, aluminum 12% by weight), Inconel 600 (nickel 76% by weight, chromium 15.5% by weight, iron 8% by weight), Inconel 65
7 (48% by weight nickel, 50% by weight chromium), cupro nickel C-7150 (30% by weight nickel, 70% by weight copper), nickel 200 (99.5% by weight nickel, 0.08% by weight carbon),
Monel 400 (66.5% by weight nickel, 31.5% by weight copper, 2 iron
(% By weight), metallic materials such as glass, and Teflon. The portion forming the material having a composition with an iron content of 20% or less may be integrally formed with these materials, but a layer of these materials may be formed on the surface by plating, thermal spraying, cladding, or the like. The same effect can be obtained by forming the. In addition, these materials have an iron content of 20
It is also possible to select and use some of the materials having a content of not more than%.

Further, in the present invention, in the second polycondensation reaction step, the material of at least the portion of the reaction apparatus for carrying out the transesterification reaction, which is substantially in contact with the reaction mixture, has an Fe content of more than 20%, and further an Fe content of 30%. The above is enough. Specific examples of such materials include SUS-304 (nickel 8% by weight, iron 74% by weight, chromium 18% by weight), SUS-316 (nickel 12% by weight, molybdenum 2% by weight, iron 68% by weight, chromium
18% by weight), SS (100% by weight of iron), Incoloy 825 (42% by weight of nickel, 2.2% by weight of molybdenum, 30% by weight of iron,
Chromium 21.5% by weight, copper 2.2% by weight), Incoloy 800
(Nickel 32.5 wt%, Iron 46.5 wt%, Chromium 21 wt%), Carpenter 20 (Nickel 35 wt%, Molybdenum
2.5 wt%, 37 wt% iron, 20 wt% chromium, 3.5 wt% copper) and the like. Further, although these materials may be integrally formed as in the first polycondensation reaction step, they may be plated, sprayed or clad.

Next, a process for producing a polycarbonate by the melt transesterification reaction will be briefly described with reference to an example of the polycarbonate shown in the drawings. FIG. 1 shows an example of a process for producing a polycarbonate by a melt transesterification reaction, which is an example using a first reactor (1) and a second reactor (2). Each reactor has a stirring blade (3), heating jacket (4), vacuum piping (5), gear pump (6), condenser (7).
, Equipped with a nitrogen inlet pipe (8). The vacuum pipe removes the monovalent hydroxy compound produced as a by-product with the progress of the reaction from the reactor, and the monovalent hydroxy compound is condensed and collected and separated by the condenser. The gear pump is a device for sending the generated resin.

A tank type reactor is generally used as the first reactor. In addition, since the second reactor handles high-viscosity resin,
It is preferred to use a device such as a vented horizontal extruder. Generally, the first polycondensation reaction step is a batch method, while the second polycondensation reaction step is a continuous method in order to increase the polymer production capacity. However, both reactors can be operated in either batch type or continuous type.
A pipe may be connected between the first reactor and the second reactor, or the resin may be once taken out from the first reactor and solidified, then melted again and sent to the second reactor. In the latter case, a degassing device may be incorporated between the resin melting device and the second reactor. The deaerator here may be a thin-film evaporator or a vented extruder type. The deaerator may be used under normal pressure, but preferably under reduced pressure.

Next, the polymerization conditions in the present invention will be described. First, the divalent hydroxy compound and the carbonic acid diester are fed into the first reactor, and a catalyst is added to the first reactor to allow the transesterification reaction to proceed. The reaction temperature in the first polycondensation reaction step is in the range of 60 to about 300 ° C. Preferably
It is in the range of 130 to 280 ℃. If it is lower than 130 ° C, the reaction rate becomes slow, and if it exceeds 280 ° C, side reactions are likely to occur. The pressure in the reaction tank during the reaction should be 0.1 to 0.1
It is in the range of torr. If this pressure is too high 1
Unable to efficiently remove the valent hydroxy compound,
On the contrary, if the pressure is too low, the carbonic acid diester or divalent hydroxy compound as a monomer will distill out,
As a result, the molar ratio of the reactive terminals changes, making it difficult to obtain a high molecular weight polymer.

Next, the second polycondensation reaction step will be described. First, the resin obtained in the first reactor is sent to the second reactor in a molten state using a gear pump. The reaction temperature in the second polycondensation reaction step ranges from 200 to about 310 ° C. It is preferably in the range of 220 to 300 ° C. If the temperature is lower than 220 ° C, the reaction rate becomes slow and the melt viscosity of the resin becomes high, so that it becomes difficult to efficiently remove the monovalent hydroxy compound by-produced. If it is higher than 300 ° C, side reactions are likely to occur. The pressure in the reactor during the reaction is 10 torr or less. It is preferably 1 torr or less. More preferably, it is 0.5 torr or less. If this pressure is too high, the monovalent hydroxy compound produced as a by-product cannot be removed efficiently.

In the method of the present invention, as a representative example of the divalent hydroxy compound used as one of the raw materials,
2-bis (4-hydroxyphenyl) propane, 2,2-
Bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis- (4-hydroxyphenyl) octane, 4,4'-dihydroxy-2,2,2-triphenylethane, 2,2-bis- (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis- (4-hydroxy-3)
-Methylphenyl) propane, 2,2-bis- (4-hydroxy-3-isopropylphenyl) propane, 2,2-
Bis (4-hydroxy-3-sec.butylphenyl) propane, 2,2-bis (4-hydroxy-3-tert.butylphenyl) propane, 1,1′-bis- (4-hydroxyphenyl) -p- Diisopropylbenzene, 1,1'-bis-
(4-hydroxyphenyl) -m-diisopropylbenzene, 1,1′-bis- (4-hydroxyphenyl) cyclohexane and the like can be mentioned.

Of these, 2,2-bis- (4-hydroxyphenyl) propane is particularly preferable.

Further, it is also possible to produce a copolycarbonate in which two or more divalent hydroxy compounds selected from these are combined.

As a typical example of carbonic acid diester,
Diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate,
Examples thereof include dicyclohexyl carbonate. Of these, diphenyl carbonate is particularly preferable.

When the polycarbonate is produced in the present invention, the above carbonic acid diester is required to be equimolar to the divalent hydroxy compound present in the reaction system. Generally, 1 mol of the carbonate compound and 1 mol of the divalent hydroxy compound must react to produce a high molecular weight polycarbonate. With diphenyl carbonate, 2 mol of phenol are produced by the reaction.
These 2 moles of phenol are distilled out of the reaction system.

However, when the produced monovalent hydroxy compound is distilled out of the system to promote the reaction, the carbonic acid diester which is a monomer may also be distilled off at the same time, and therefore the carbonic acid diester used is divalent. 1.01 to 1.5 mol, preferably 1.0 per mol of phenol
It is preferably used in an amount of 15 to 1.20 mol.

In the present invention, when a polycarbonate is produced in the presence of an ester exchange catalyst using the above divalent hydroxy compound and carbonic acid diester, a carbonic acid diester compound, an ester compound, or It is also possible to add a phenol compound or the like. The amount of these end-capping agents used is 0.05 to 10 mol%, preferably 1 to 5 mol% based on the divalent hydroxy compound.
It should be

Examples of the transesterification catalyst that can be used in the present invention include electron-donating amine compounds, alkali metal compounds and alkaline earth metal compounds, and borate salts.
And Na, K, Be, Ca, Sr, Ba, Zn, Cd, Al, Cr, M
Metals such as o, Fe, Co, Ni, Ag, Au, Sn, Sb, Pb, Pt and Pd, and alcoholates, oxides, carbonates, acetates, hydrides and the like can also be used.

Typical examples of the electron-donating amine compound are 4-dimethylaminopyridine, 4-diethylaminopyridine, 4-pyrrolidinopyridine, 4-aminopyridine, 2-hydroxypyridine, 4-hydroxypyridine and 2-methoxypyridine. , 4-methoxypyridine, 2
-Methoxyimidazole, 1-methylimidazole, imidazole, aminoquinoline, 4-methylimidazole, diazabicyclooctane (DABCO) and the like can be mentioned.

Typical examples of the alkali metal compounds and alkaline earth metal compounds are sodium hydroxide, lithium hydroxide, potassium hydroxide, sodium hydrogen carbonate, lithium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, lithium carbonate, potassium carbonate. , Sodium acetate, lithium acetate, potassium acetate, sodium stearate, lithium stearate, potassium stearate, sodium borohydride, lithium borohydride, potassium borohydride, sodium benzoate, lithium benzoate, potassium benzoate, water Barium oxide, calcium hydroxide, magnesium hydroxide, barium hydrogen carbonate, calcium hydrogen carbonate, magnesium hydrogen carbonate, barium carbonate, calcium carbonate, magnesium carbonate, barium acetate, calcium acetate, magnesium acetate Barium stearate, calcium stearate, magnesium stearate, and the like.

Typical examples of borate salts are sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, lithium metaborate, lithium tetraborate, lithium pentaborate. , Potassium metaborate, potassium tetraborate, potassium pentaborate,
Potassium hexaborate, potassium octaborate, ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate, ammonium borate, tetramethylammonium borate, aluminum potassium borate, cadmium borate, boric acid Examples thereof include silver, copper borate, lead borate, nickel borate, magnesium borate, and manganese borate.

These transesterification catalysts may be used alone or in combination of two or more. When plural catalysts are used in combination, the catalysts may be added at the same time when the monomers are charged, or may be added stepwise during the reaction.

The amount of the transesterification catalyst used is required to be 10 ^-8 to 10 ^-1 mol, preferably 10 ^-7 to 10 ^-2 mol, per 1 mol of the dihydric phenol present in the reaction system. . 10 ^-8
If it is less than 10 mol, the catalytic action will be small and the polymerization rate of the polycarbonate will be slow. If it is more than 10 ^-1 mol, the residual rate in the polycarbonate produced will be high, and the physical properties of the polycarbonate will be likely to deteriorate.

Typical examples of boric acid or boric acid ester added to the reaction mixture include boric acid, triphenyl borate, trimethyl borate, triethyl borate, butyl borate, and tritolyl borate. These boric acid or boric acid ester may be added at the beginning of the reaction, or may be added during the reaction or after the completion of the reaction. These boric acid or boric acid ester,
It has the effect of neutralizing the basic polymerization catalyst and increasing the thermal stability of the polymer. The amount of these boric acid or boric acid ester used is 1 × 10 ^-2 to 1 × 10 6 with respect to 1 mol of the catalyst used.
You need ³ moles. If it is less than 1 × 10 ⁻² mol, the effect of heat stabilization is not exerted, and if it exceeds 1 × 10 ³ mol, the degree of polymerization cannot be increased, which is not preferable.

[0034]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited by these examples.

First, the methods for measuring and evaluating the intrinsic viscosity [η], the hue, and the concentration of the monovalent hydroxy compound in the polymer described in Examples and Comparative Examples will be described. Intrinsic viscosity [η]: A 0.5% methylene chloride solution of the polymer was measured at 20 ° C. using an Ubbelohde viscometer and evaluated. Hue: 10% of polymer by UV spectroscopy
It was evaluated by measuring the difference A ₃₈₀ -A ₅₈₀ of absorbance at 380nm and 580nm of methylene chloride solution. As the hue value,
It is preferably 1.0 or less. Concentration of monovalent hydroxy compound in polymer Measurement was carried out by gas chromatography (Shimadzu Corporation GC-14A) using silicon OV-210 as a stationary phase.

Example 1 2,2-bis (4-hydroxyphenyl) propane 4.57 kg
(20 mol), 4.39 kg (20.5 mol) of diphenyl carbonate and 0.489 g (0.004 mol) of 4-dimethylaminopyridine made of Hastelloy C-276 (Fe content of 5.5
(Wt%) in a tank reactor, melt at 160 ° C under nitrogen, stir well, raise the temperature while gradually reducing the pressure, distilling off the phenol produced, and finally making the reaction 1 torr, 260 ° C. Was advanced to obtain a prepolymer. The intrinsic viscosity [η] of the prepolymer is 0.3 dl / g, and the hue value is A ₃₈₀ -A _580.
= 0.06, the phenol concentration in the prepolymer was 350 ppm. This prepolymer was sent from the bottom of the reactor via a gear pump to a horizontal polycondensation reaction tank made of stainless steel (SUS-316) (Fe content 68% by weight) controlled at 280 ° C and 0.1 torr and retained. The reaction was carried out continuously for 50 minutes. The obtained resin was colorless and transparent. The intrinsic viscosity [η] of the polymer is 0.5 dl / g, and the hue value is A ₃₈₀ -A ₅₈₀ =
0.09, the phenol concentration in the polymer was 30 ppm.

Example 2 22.8 g of 2,2-bis (4-hydroxyphenyl) propane
(0.1 mol), diphenyl carbonate 21.9g (0.1025
Mol) and 0.098 mg (1 × 10 ⁻⁶ mol) of potassium acetate in a flask made of Inconel 600 (Fe content 8% by weight), melt under nitrogen at 180 ° C., stir well and raise the temperature gradually while reducing the pressure. Finally, the temperature was adjusted to 1 torr and 260 ° C., and the produced phenol was distilled off to obtain a colorless and transparent prepolymer. The intrinsic viscosity [η] of the prepolymer was 0.35 dl / g, the hue value was A ₃₈₀ -A ₅₈₀ = 0.07, and the phenol concentration in the prepolymer was 830 ppm. This prepolymer is then placed in a flask made of Incoloy 800 (Fe content 46.5% by weight),
The reaction was carried out at 280 ° C and 0.1 torr. The obtained resin was colorless and transparent. The intrinsic viscosity [η] of the polymer is 0.52dl /
g, a hue value A ₃₈₀ -A ₅₈₀ = 0.08, phenol concentration in the polymer was 20 ppm.

Example 3 The material of the reactor was changed to that shown in Table 1, and the catalyst was 4-dimethylaminopyridine 2.48 mg (2 × 10 ⁻⁵ mol) and sodium hydroxide 0.02 mg (5 × 10 ⁻⁷ mol). The same polymerization experiment as in Example 2 was carried out, except that The obtained resin was colorless and transparent. Other results are shown in Table 1.

Example 4 Polymerization experiment similar to that of Example 2 except that the material of the reactor was changed to that shown in Table 1 and the catalyst was changed to 0.145 mg (7.2 × 10 ⁻⁷ mol) of sodium tetraborate. I went. The obtained resin was colorless and transparent. Other results are shown in Table 1.

Example 5 Except that the material of the reactor was changed to that shown in Table 1 and the catalyst was changed to sodium hydroxide 0.16 mg (4 × 10 ⁻⁶ mol).
The same polymerization experiment as in Example 2 was conducted. The obtained resin was colorless and transparent. Other results are shown in Table 1.

Example 6 The material of the reactor was changed to that shown in Table 1, the catalyst was changed to 0.05 mg of potassium acetate (5 × 10 ⁻⁷ mol), and 0.31 mg (5 × 10 5) of boric acid was further added at the initial stage of the reaction. ^-6 mol) was added, and the same polymerization experiment as in Example 2 was carried out. The obtained resin was colorless and transparent. Other results are shown in Table 1.

Comparative Example 1 Polymerization similar to Example 2 except that the material of the reactor was changed to that shown in Table 1 and the catalyst was changed to 2.48 mg (2 × 10 ⁻⁵ mol) of 4-dimethylaminopyridine. An experiment was conducted. The resulting resin was red. Other results are shown in Table 1.

Comparative Example 2 Except that the material of the reactor was changed to that shown in Table 1 and the catalyst was changed to 0.16 mg (4 × 10 ⁻⁶ mol) of sodium hydroxide,
The same polymerization experiment as in Example 2 was conducted. The resulting resin was red. Other results are shown in Table 1.

Comparative Example 3 The same polymerization experiment as in Example 2 was carried out except that the material of the reactor was changed to that shown in Table 1 and the catalyst was changed to 0.05 mg of potassium acetate (5 × 10 ⁻⁷ mol). It was The resulting resin was red. Other results are shown in Table 1.

Comparative Example 4 Except that the material of the reactor was changed to that shown in Table 2 and the catalyst was changed to sodium hydroxide 0.16 mg (4 × 10 ⁻⁶ mol).
The same polymerization experiment as in Example 2 was conducted. The resulting resin was red. Other results are shown in Table 2.

[0046]

[Table 1]

[0047]

[Table 2]

[Brief description of drawings]

FIG. 1 is a diagram showing a polycarbonate production process by a melt transesterification reaction.

[Explanation of symbols]

 1 1st reactor 2 2nd reactor 3 Stirring blade 4 Heating jacket 5 Vacuum piping 6 Gear pump 7 Condenser 8 Nitrogen introduction pipe

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[Procedure amendment]

[Submission date] July 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Next, a process for producing a polycarbonate by the melt transesterification reaction will be briefly described with reference to an example of the polycarbonate shown in the drawings. FIG. 1 shows an example of a process for producing a polycarbonate by a melt transesterification reaction, which is an example using a first reactor (1) and a second reactor (2). Each reactor has a stirring blade (3), heating jacket (4), vacuum piping (5), gear pump (6), condenser (7).
, Equipped with a nitrogen inlet pipe (8). The vacuum pipe removes the monovalent hydroxy compound produced as a by-product with the progress of the reaction from the reactor, and the monovalent hydroxy compound is condensed and collected and separated by the condenser. As the material of the vacuum piping
For SUS-316, SUS-316L, SUS-304, SUS-304L,
Applying Kanigen plating (electroless nickel plating)
Is preferred. The gear pump is a device for sending the generated resin.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

A tank type reactor is generally used as the first reactor. In addition, since the second reactor handles high-viscosity resin,
It is preferred to use a device such as a vented horizontal extruder. Generally, the first polycondensation reaction step is a batch method, while the second polycondensation reaction step is a continuous method in order to increase the polymer production capacity. However, both reactors can be operated in either batch type or continuous type.
During the first reactor and the second reactor rather good connected even if <br/> a pipe, the material of the pipe, SUS-316, SUS-316L , SUS-
304, SUS-304L with Kanigen plating (electroless nickel
Kel plating) is preferable. Alternatively , the resin may be once taken out from the first reactor and solidified, then melted again and sent to the second reactor. In the latter case, a degassing device may be incorporated between the resin melting device and the second reactor. The deaerator here may be a thin-film evaporator or a vented extruder type. The deaerator may be used at normal pressure,
It is preferably used under reduced pressure.

Claims (6)

[Claims] 1. When producing a polycarbonate by melt polycondensation of a divalent hydroxy compound and a carbonic acid diester in the presence of a transesterification catalyst, the material that comes into contact with the reaction mixture is an iron content in the first polycondensation reaction step. A method for producing a polycarbonate characterized in that the content of iron is 20% by weight or less and the iron content in the second polycondensation reaction step is more than 20% by weight. 2. The polymer obtained in the first polycondensation reaction step has an intrinsic viscosity [η] of 0.1 to 0.4 dl / g, and
The intrinsic viscosity [η] of the polymer obtained in the polycondensation reaction step is
The method for producing a polycarbonate according to claim 1, wherein it is 0.3 to 1.0 dl / g. 3. The concentration of the monovalent hydroxy compound in the polymer obtained in the first polycondensation reaction step is 10 ppm or more,
The method for producing a polycarbonate according to claim 1 or 2, wherein the concentration of the monovalent hydroxy compound in the polymer obtained in the second polycondensation reaction step is 10,000 ppm or less. 4. An electron-donating amine compound and / or an alkali metal compound or an alkaline earth metal compound is used as a transesterification catalyst.
The method for producing the polycarbonate according to any one of 1. 5. The method for producing a polycarbonate according to claim 1, wherein borate is used as the transesterification catalyst. 6. The method for producing a polycarbonate according to claim 1, wherein boric acid is added to the reaction mixture.