JPH07109343A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To obtain a high-quality polycarbonate having excellent transparency free from retention burn mark, by carrying out transesterification reaction by a reactor made of nickel steel, having an inner wall subjected to passive state treatment. CONSTITUTION:This polycarbonate is obtained by subjecting (A) a dihydroxy compound such as a compound of formula I (R is halogen or 11-8C alkyl; Z is single bond and 1-8C alkylene, 2-8C alkylidene, etc.; (m) is 0-4) and (B) a carbonic acid diester such as a compound of formula II (Ar<2> is aryl) to transesterification reaction by using a reactor made of nickel steel, having an inner wall subjected to passive state treatment.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polycarbonate. Specifically, in producing a polycarbonate from a dihydroxy compound and a carbonic acid diester by a transesterification method, by passively treating the inner wall of a nickel steel reactor, excellent quality without retention scoring and color tone (transparency) are obtained. The present invention relates to a method for efficiently producing an excellent polycarbonate.

[0002]

2. Description of the Related Art Generally, a method for producing a polycarbonate (hereinafter sometimes referred to as PC) is a method of directly reacting an aromatic dihydroxy compound such as bisphenol A with phosgene ( An interfacial polycondensation method) or a method (melting method) in which an aromatic dihydroxy compound such as bisphenol A and a carbonic acid diester such as diphenyl carbonate are transesterified in a molten state is known. In the interfacial polycondensation method in the production method of PC, toxic phosgene must be used, the production equipment is corroded by chlorine-containing compounds such as hydrogen chloride and sodium chloride produced as a by-product, and hydroxylation mixed in the resin. There are various problems such as difficulty in separating impurities such as sodium that adversely affect the physical properties of the polymer.

On the other hand, the melting method has an advantage that PC can be manufactured at a lower cost than the interfacial polycondensation method, but usually, the reaction is carried out at a high temperature of 280 to 310 ° C. for a long time. In addition, it has a big drawback that it cannot escape from the coloring problem of the resin. In such a melting method, various improved techniques have been proposed in order to reduce this coloring. For example, JP-B-61-39972 and JP-A-63-223036 disclose a method of using a specific catalyst. Also, JP-A-61-151
Japanese Patent Laid-Open No. 236 and Japanese Patent Laid-Open No. 62-158719 disclose a method of adding an antioxidant in the latter stage of the reaction. And, in JP-A-61-62522, etc.,
In the latter stage of the reaction, a twin-screw vent type kneading extruder was used.
Japanese Patent Laid-Open No. 153925 discloses a process improvement technique such as using a horizontal stirring polymerization tank. Further, Japanese Patent Application Laid-Open No. 2-175722 discloses a method in which the content of hydrolyzable chlorine in a monomer is set to a certain level or less. Further, in order to improve the hydrolysis resistance of the obtained PC, it has been conventionally known to neutralize with a volatile acid such as dimethylsulfate, and recently, with an acid such as p-toluenesulfonic acid. There is known a technique of neutralizing and neutralizing an excess acid with an epoxy (JP-A-4-175368). However, the problem of coloring has not been completely solved yet, and the actual situation is that a satisfactory PC has not been obtained yet.

[0004]

Therefore, the present inventors have
In view of the above situation, the inventors have conducted earnest studies to solve the above-mentioned drawbacks of the conventional method and to develop a method for producing a polycarbonate capable of efficiently producing a PC having an excellent color tone by the melt transesterification method. As a result, they have found that the above problem can be solved by specially treating the inner wall of the nickel (Ni) steel reactor in the method for producing PC by the transesterification method. The present invention has been completed based on such findings. That is, the present invention is
In producing a polycarbonate from a (A) dihydroxy compound and a (B) carbonic acid diester by a transesterification method, a passivation treatment is applied to an inner wall of a nickel steel reactor for performing the transesterification reaction. Is provided.

In the present invention, there are various dihydroxy compounds used as the component (A). For example, selected from aromatic dihydroxy compounds, aliphatic dihydroxy compounds, bisesters of aromatic dihydroxy compounds, bisesters of aliphatic dihydroxy compounds, carbonates of aromatic dihydroxy compounds, and carbonates of aliphatic dihydroxy compounds. At least one compound. The aromatic dihydroxy compound used as one of the components (A) has the general formula (I)

[0006]

[Chemical 1]

[Wherein R is a halogen atom (for example, chlorine, bromine, fluorine, iodine) or an alkyl group having 1 to 8 carbon atoms (for example, methyl group, ethyl group, propyl group, n-butyl group, Isobutyl group, amyl group, isoamyl group, hexyl group, etc.) and when this R is plural,
They may be the same or different,
m is an integer of 0-4. Z is a single bond, an alkylene group having 1 to 8 carbon atoms or an alkylidene group having 2 to 8 carbon atoms (eg, methylene group, ethylene group, propylene group, butylene group, penterylene group, hexylene group, ethylidene group, isopropylidene group). Ridene group, etc., 5 to 15 carbon atoms
Cycloalkylene group or cycloalkylidene group having 5 to 15 carbon atoms (for example, cyclopentylene group, cyclohexylene group, cyclopentylidene group, cyclohexylidene group, etc.), or -S-, -SO-, -SO ₂ -, -O
-, -CO- bond or general formula (II) or (II ')

[0008]

[Chemical 2]

The bond represented by ] The aromatic dihydroxy compound represented by these is mentioned. Examples of such aromatic dihydroxy compounds include bis (4-hydroxyphenyl) methane; 1,1-bis (4-hydroxyphenyl) ethane; 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A : BPA);
2,2-bis (4-hydroxyphenyl) butane; 2,
2-bis (4-hydroxyphenyl) octane; 2,2
-Bis (4-hydroxyphenyl) phenylmethane;
2,2-bis (4-hydroxy-3-methylphenyl)
Propane; 1,1-bis (4-hydroxy-t-butylphenyl) propane; 2,2-bis (4-hydroxy-)
3-Bromophenyl) propane; 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane; 2,
2-bis (4-hydroxy-3-chlorophenyl) propane; 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane; 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane Such as bis (hydroxyaryl) alkanes; 1,1-bis (4-hydroxyphenyl) cyclopentane; 1,1-bis (4
-Hydroxyphenyl) cyclohexane; 1,1-bis (4-hydroxyphenyl) -3,5,5-trimethylcyclohexane and other bis (hydroxyaryl) cycloalkanes; 4,4-dihydroxydiphenyl ether; 4,4'-dihydroxy Dihydroxy aryl ethers such as -3,3'-dimethylphenyl ether;
4,4'-dihydroxydiphenyl sulfide; 4,
Dihydroxydiaryl sulfides such as 4'-dihydroxy-3,3'-dimethyldiphenyl sulfide;
4,4'-dihydroxydiphenyl sulfoxide; 4,
Dihydroxyaryl sulfoxides such as 4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; 4,4'-dihydroxydiphenyl sulfone; 4,
Dihydroxydiarylsulfones such as 4'-dihydroxy-3,3'-dimethyldiphenylsulfone, dihydroxybenzene, halogen and alkyl-substituted dihydroxybenzenes such as 1,4-dihydroxy-2,5-
Dichlorobenzene; 1,4-dihydroxy-3-methylbenzene and the like can be mentioned.

There are various kinds of aliphatic dihydroxy compounds as the component (A). For example, butane-1,4-diol; 2,2-dimethylpropane-
1,3-diol; hexane-1,6-diol; diethylene glycol; triethylene glycol; tetraethylene glycol; octaethylene glycol; dipropylene glycol; N, N-dimethyldiethanolamine; cyclohexane-1,3-diol; cyclohexane -1,4-diol; 1,4-dimethylolcyclohexane; p-xylylene glycol; 2,2-bis-
Ethoxylated or propoxylated products of (4-hydroxycyclohexyl) -propane and dihydric alcohols or phenols such as bis-oxyethyl-bisphenol A; bis-oxyethyl-tetrachlorobisphenol A or bis-oxyethyl-tetrachlorohydroquinone. To be

Examples of the bisester of an aromatic dihydroxy compound, the bisester of an aliphatic dihydroxy compound, the carbonate of an aromatic dihydroxy compound, or the carbonate of an aliphatic dihydroxy compound used as the component (A) include The bisesters of the above compounds have the general formula (III)

[0012]

[Chemical 3]

[Wherein R ¹ represents a residue obtained by removing two hydroxyl groups from the above aliphatic dihydroxy compound, and R ² represents an alkyl group having 1 to 6 carbon atoms or 4 to 4 carbon atoms.
A cycloalkyl group having 7 is shown. ] The compound represented by the general formula (IV)

[0014]

[Chemical 4]

[In the formula, Ar ¹ represents a residue obtained by removing two hydroxyl groups from the aromatic dihydroxy compound, and R ² has the same meaning as described above. ] The compound represented by the general formula (V)

[0016]

[Chemical 5]

[In the formula, Ar ² represents an aryl group, and R ¹ is the same as above. ] Or a compound represented by the general formula (V
I)

[0018]

[Chemical 6]

[In the formula, Ar ¹ and Ar ² are the same as defined above. ] The compound represented by these is mentioned. Further, the carbonates of the above compounds have the general formula (VII)

[0020]

[Chemical 7]

[In the formula, R ¹ and R ² are the same as defined above. ] The compound represented by the general formula (VIII)

[0022]

[Chemical 8]

[In the formula, R ² and Ar ¹ are the same as defined above. ] The compound represented by the general formula (IX)

[0024]

[Chemical 9]

[In the formula, R ¹ and Ar ² are the same as defined above. ] The compound or general formula (X) represented by

[0026]

[Chemical 10]

[In the formula, Ar ¹ and Ar ² are the same as defined above. ] The compound represented by these is mentioned. In the present invention, as the dihydroxy compound as the component (A), the above compounds are appropriately selected and used. Among these, it is preferable to use bisphenol A which is an aromatic dihydroxy compound. When bisphenol A is used, an adduct of bisphenol A and phenol or a mixture of the adduct and phenol can be used.

On the other hand, in the present invention, there are various carbonic acid diesters used as the component (B). For example, it is at least one compound selected from diaryl carbonate compounds, dialkyl carbonate compounds or alkylaryl carbonate compounds. The diaryl carbonate compound used as one of the components (B) has the general formula (XI)

[0029]

[Chemical 11]

[In the formula, Ar ² is the same as described above. ] The compound or general formula (X) represented by

[0031]

[Chemical 12]

[In the formula, Ar ¹ and Ar ² are the same as defined above. ] It is a compound represented by these. The dialkyl carbonate compound has the general formula (XII)

[0033]

[Chemical 13]

[In the formula, R ² is the same as above. ] Or a compound represented by the general formula (VIII)

[0035]

[Chemical 14]

[In the formula, R ² and Ar ¹ are the same as defined above. ] It is a compound represented by these. The alkyl aryl carbonate compound has the general formula (XIII)

[0037]

[Chemical 15]

[In the formula, R ² and Ar ² are the same as defined above. ] Or a compound represented by the general formula (XIV)

[0039]

[Chemical 16]

[In the formula, R ² , Ar ¹ and Ar ² are the same as defined above. ] It is a compound represented by these. Here, examples of the carbonic acid diaryl compound include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, and bisphenol A bisphenyl carbonate.
Examples of the dialkyl carbonate compound include diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, bisphenol A bismethyl carbonate and the like. Examples of the alkyl aryl carbonate compound include methylphenyl carbonate, ethylphenyl carbonate, butylphenyl carbonate, cyclohexylphenyl carbonate, bisphenol A methylphenyl carbonate and the like. Among these, diphenyl carbonate is particularly preferable. In the present invention,
As the carbonic acid diester as the component (B), the above compounds are appropriately selected and used, but among these, diphenyl carbonate is preferably used.

The production method of the present invention is to obtain a polycarbonate by a transesterification reaction using the components (A) and (B). In order to produce a polycarbonate by this transesterification reaction, in addition to the above-mentioned components (A) and (B), if necessary, the following terminal terminator can be used. Specific examples of such an end terminating agent include on-butylphenol; mn-
Butylphenol; pn-butylphenol; o-isobutylphenol; m-isobutylphenol; p-
Isobutylphenol; ot-butylphenol; m
-T-butylphenol; pt-butylphenol;
nn-pentylphenol; mn-pentylphenol; pn-pentylphenol; nn-hexylphenol; mn-hexylphenol; pn-hexylphenol; o-cyclohexylphenol; m
-Cyclohexylphenol; p-cyclohexylphenol; o-phenylphenol; m-phenylphenol; p-phenylphenol; nn-nonylphenol; mn-nonylphenol; pn-nonylphenol; o-cumylphenol; m- Cumylphenol; p-cumylphenol; o-naphthylphenol;
m-naphthylphenol; p-naphthylphenol;
2,6-di-t-butylphenol; 2,5-di-t-
Butylphenol; 2,4-di-t-butylphenol; 3,5-di-t-butylphenol; 2,5-dicumylphenol; 3,5-dicumylphenol; formula

[0042]

[Chemical 17]

Examples of the compound represented by

[0044]

[Chemical 18]

Examples thereof include monohydric phenols. Of these phenols, although not particularly limited in the present invention, p-tert-butylphenol; p-cumylphenol and the like are preferable. Also, the formula

[0046]

[Chemical 19]

Examples thereof include compounds represented by Furthermore, in the present invention, phloroglucin; trimellitic acid; 1,1,1-tris (4-hydroxyphenyl) ethane; 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl], if necessary. -4- [α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene; α,
α ′, α ″ -tris (4-hydroxyphenyl) -1,
3,5-triisopropylbenzene; isatin bis (o
-Cresol) or the like can be used as a branching agent.
Further, although a catalyst is not particularly required in the present invention, a known catalyst may be used for promoting the transesterification reaction. Specific examples of such a catalyst include simple substance of alkali metal or alkaline earth metal, oxide, hydroxide, amide compound, alcoholate, phenolate, or Zn.
Basic metal oxides such as O, PbO and Sb ₂ O ₃ , organic titanium compounds, soluble manganese compounds, Ca, Mg,
Acetates of Zn, Pb, Sn, Mn, Cd, Co or nitrogen-containing basic compounds and boron compounds, nitrogen-containing basic compounds and alkali (earth) metal compounds, nitrogen-containing basic compounds and alkali (earth) metals Examples thereof include a combined catalyst of a compound and a boron compound.

In the production method of the present invention, when a polycarbonate is produced by a transesterification reaction using the above-mentioned component (A), component (B) and a terminal stopper or a branching agent as other components, the transesterification reaction is carried out. A major feature of the reactor is a nickel (Ni) steel reactor whose inner wall is passivated. Where usually
There are various types of reactors for transesterification, but in the present invention, a nickel steel reactor is particularly used. Then, the inner wall of the nickel steel reactor is passivated before use. As a reactor, if the transesterification reaction is carried out without passivating the inner wall of the nickel steel reactor, or if the transesterification reaction is carried out using a SUS reactor, hydrolysis resistance and retention burning are inferior, and A carbonate having a poor color tone is obtained. In the present invention, the surface of the inner wall of the nickel steel reactor (in particular, the inner wall with which the raw material components or the produced polymer comes into contact) may be passivated. Alternatively, if the surface of the contact portion of the extruder or the like is passivated, the effect will be further enhanced. Here, as the accessory device, for example, a stirring blade or a shaft equipped in the reactor, instrumentation parts such as a temperature sensor, a pipe portion adjacent to the reactor or a pipe member (for example, a flange)
Alternatively, a cylinder or screw of an extruder may be used.

In the present invention, various methods can be adopted as the method for passivating the inner wall of the nickel steel reactor, but a known method suitable for nickel steel may be used. Specifically, the following method can be mentioned. Method of forming an oxide film with sodium dichromate, sodium hydroxide, ammonia, etc. Method of adding antimony compound (for example, antimony trisdialkyldithiophosphite or antimony pentoxide sol decomposed in organic solvent) Treatment with sodium sulfide aqueous solution After that, the temperature is raised to form a nickel sulfide film.

In the production method of the present invention, specifically, the reaction proceeds according to a known transesterification method. The procedure and conditions of the production method of the present invention will be specifically described below. That is, as described above, in a nickel steel reactor whose inner wall is passivated, for example, in a laboratory, a nickel steel autoclave whose inner wall is passivated is prepared by first adding a dihydroxy compound (A) and (B). ) Component carbonic acid diester is charged in a ratio such that the carbonic acid diester is 1 to 1.5 times the molar amount of the dihydroxy compound, and then a normal transesterification reaction is carried out. Depending on the situation, the amount of the carbonic acid diester is preferably 1.02 to 1.20 times the molar amount of the dihydroxy compound, which is slightly excessive.

In the above-mentioned transesterification reaction, the amount of the terminal terminator composed of the monohydric phenol, etc.
With respect to 1 mol of the dihydroxy compound which is the component (A),
When the amount is in the range of 0.05 mol% to 10 mol%, the hydroxyl group terminal of the obtained polycarbonate is sealed, so that a polycarbonate having sufficiently excellent heat resistance and water resistance can be obtained. The total amount of such a terminal terminator composed of the monohydric phenol may be added to the reaction system in advance. Further, it may be added in part to the reaction system in advance and the rest may be added as the reaction progresses. Further, in some cases, the whole amount may be added to the reaction system after the transesterification reaction of the dihydroxy compound (A) and the carbonic acid diester (B) partially proceeds.

In carrying out the transesterification reaction according to the method of the present invention, the reaction temperature is not particularly limited,
It is usually in the range of 100 ° C to 330 ° C, preferably 18 ° C.
A method of raising the temperature from 0 ° C to 300 ° C, more preferably 180 ° C to 300 ° C gradually according to the progress of the reaction is preferable. If the transesterification reaction is lower than 100 ° C., the progress of the reaction is slow, and if it exceeds 330 ° C., thermal deterioration of the polymer may occur, which may not be preferable. The reaction pressure is set according to the vapor pressure of the monomer used and the reaction temperature. This is not limited as long as it is set so that the reaction can be efficiently performed. Usually, in the initial stage of the reaction, 1 to 50 atm (760 to 38,000 to
rr) to atmospheric pressure or pressurized condition, and in the latter half of the reaction, reduced pressure condition, preferably 0.01 to
It is often 100 torr. Further, the reaction time may be such that it reaches the target molecular weight, and is usually about 0.2 to 10 hours.

The above reaction is carried out in the absence of an inert solvent, but if necessary, 1 to
It may also be carried out in the presence of 150% by weight of an inert solvent. Here, examples of the inert solvent include aromatic compounds such as diphenyl ether, halogenated diphenyl ether, benzophenone, polyphenyl ether, dichlorobenzene, and methylnaphthalene, carbon dioxide, gases such as dinitrogen monoxide and nitrogen, and chlorofluorohydrocarbons. Examples thereof include alkanes such as ethane and propane, cyclohexane, cycloalkanes such as tricyclo (5,2,10) -decane, cyclooctane and cyclodecane, and alkenes such as ethene and propene.

In the present invention, an antioxidant can be used if necessary. Specific examples include phosphorus-based antioxidants such as tris (nonylphenyl) phosphite, trisphenylphosphite, 2-ethylhexyldiphenylphosphite, trimethylphosphite, triethylphosphite, tricresylphosphite, and triarylphosphite. There is.

In the present invention, as the reaction proceeds, phenols corresponding to the carbonic acid diester used,
Alcohols or their esters and inert solvent are desorbed from the reactor. These desorbed substances are separated,
It can be purified and recycled, and it is preferable to have a facility for removing these. And, the present invention can be carried out batchwise or continuously, and any equipment can be used. In the case of continuous production, it is preferable to use at least two reactors and set the above reaction conditions. The reactor used in the present invention is provided with a coating film of the above-mentioned material on the inner wall thereof, and the structure thereof is not particularly limited, but may have a normal stirring function. However, since the viscosity increases in the latter stage of the reaction, it is preferable to have a high-viscosity stirring function. Further, the shape of the reactor is not limited to a tank type, and may be an extruder type reactor or the like.

The PC thus obtained may be granulated as it is, or may be molded by using an extruder or the like. Further, the PC obtained by the present invention can be used by blending well-known additives such as a plasticizer, a pigment, a lubricant, a release agent, a stabilizer and an inorganic filler. Further, the obtained PC can be blended with a polymer such as polyolefin, polystyrene, polyester, polysulfonate, polyamide and polyphenylene oxide. In particular, OH group, COOH group, NH ₂
It is effective when used in combination with a polyphenylene ether having an end group such as a group, a polyether nitrile, a terminal-modified polysiloxane compound, a modified polypropylene, and a modified polystyrene.

[0057]

The present invention will be further described in detail with reference to Examples and Comparative Examples. The present invention is not limited to the examples below. Example 1 Passivation treatment (150 g of sodium dichromate and 200 ml of nitric acid to which 1 liter of water was added to make it 1 liter and immersed for 3 minutes at room temperature) nickel autoclave (stirrer) made of nickel (Ni) steel with an internal volume of 1.4 liters 228 g (1.00 mol) of bisphenol A (BPA) and 257 g (1.2 mol) of diphenyl carbonate were charged to the unit), and nitrogen substitution was carried out 5 times. The mixture was heated to 180 ° C. to melt the bisphenol A and diphenyl carbonate.
Then, as a catalyst, 2.5 mg of (C ₄ H ₉ ) ₄ NBH ₄ was used.
(1 × 10 ⁻⁵ mol) was added, the temperature was raised to 220 ° C., stirring was started at the same time, and a small amount of nitrogen was passed through, and the produced phenol started to be distilled off. The temperature of the reaction product was maintained at 220 ° C. for 4 hours. After that, gradually increase the temperature from 220 ℃ to 28
At the same time as the temperature was raised to 0 ° C. over 1 hour, the degree of vacuum was raised to remove the residual diphenyl carbonate and proceed with the transesterification reaction. Finally the pressure is 0.5 to
The reaction was carried out with stirring for 1 hour while maintaining the rr, and finally, a viscous and transparent condensate (PC) was obtained in the autoclave.

Example 2 In Example 1, as a catalyst, (C ₄ H ₉ ) ₄ NBH _{4 was used.}
In place of 2.5 mg (1 × 10 ^-5 mol) of LiOH.
The procedure of Example 1 was ^repeated except that 2 mg (1 × 10 ⁻⁵ mol) was used. Example 3 The procedure of Example 1 was repeated, except that 6.8 g of p-cumylphenol (0.05 mol based on BPA) was added as a terminal stopper. Example 4 The procedure of Example 1 was repeated, except that 28.2 g of diphenyl ether was added as an inert solvent and no catalyst was used.

Comparative Example 1 Example 1 was carried out in the same manner as Example 1 except that the Ni steel autoclave which was not passivated was used. Comparative Example 2 The procedure of Example 1 was repeated, except that the passivated Ni steel autoclave was replaced with a SUS316L autoclave.

The viscous and transparent condensates (PC) obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were dissolved in methylene chloride,
The viscosity average molecular weight was measured. Further, the viscous and transparent condensates obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were crushed and pelletized at 270 ° C using an extruder. The obtained pellets were injection-molded to prepare test pieces and subjected to YI and retention burn test. Table 1 shows the measurement results of the viscosity average molecular weight and the results of the YI and retention burn test.

[0061]

[Table 1]

The viscosity average molecular weight, YI and retention burn test were as follows. 1) Viscosity average molecular weight (Mv) The viscosity of a methylene chloride solution at 20 ° C was measured with an Ubbelohde type viscosity tube, and the intrinsic viscosity [η] was calculated from this, and then calculated by the following formula. [Η] = 1.23 × 10 ⁻⁵ × Mv ^0.83 2) YI (Yellow Index) Measured using a color meter SM-3 (manufactured by Suga Test Instruments Co., Ltd.) according to JIS K-7103-77. . 3) Residence burn test YI of the molded product molded at 320 ° C and 2 in the cylinder
Evaluation was made on the basis of the difference in YI of the molded product molded after being allowed to stay for 0 minute.

[0063]

As described above, according to the present invention, by using a nickel steel reactor whose inner wall is passivated as a reactor for carrying out a transesterification reaction, it is possible to obtain excellent quality without retention scoring and to obtain a color tone (transparency). It is possible to produce a polycarbonate having excellent properties. Therefore, the present invention
It can be effectively and widely used as a method for industrially producing polycarbonate by the transesterification method.

Claims (1)

[Claims] 1. When a polycarbonate is produced from a (A) dihydroxy compound and (B) a carbonic acid diester by a transesterification method, the inner wall of a nickel steel reactor for carrying out the transesterification reaction is passivated. A method for producing a polycarbonate.