JPH073005A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To efficiently produce a polycarbonate excellent in hydrolysis resistance, storage discoloring resistance and color tone. CONSTITUTION:A method for producing a polycarbonate by subjecting (A) a dihydroxy compound and (B) a carbonic acid diester to a transesterification reaction is characterized by using (C) a metal nitride or metal carbide as the inner wall material of a reactor used for the transesterification reaction.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polycarbonate. Specifically, when a polycarbonate is produced from a dihydroxy compound and a carbonic acid diester by a transesterification method, by using a specific metal material as an inner wall material of the reactor, hydrolysis resistance is not impaired, and retention-free quality is obtained. And a method of efficiently producing a polycarbonate having excellent color tone (transparency).

[0002]

2. Description of the Related Art Generally, as a method for producing a polycarbonate (hereinafter referred to as PC), a method in which an aromatic dihydroxy compound such as bisphenol A is directly reacted with phosgene (interfacial method) Alternatively, there is known a method (melting method) in which an aromatic dihydroxy compound such as bisphenol A and a carbonic acid diester such as diphenyl carbonate are subjected to a transesterification reaction in a molten state. In the method of manufacturing PC, the interfacial method must use toxic phosgene,
There are various problems such as corrosion of production equipment by chlorine-containing compounds such as hydrogen chloride and sodium chloride produced as by-products, and difficulty in separating impurities such as sodium hydroxide mixed in the resin 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 method, but since it is usually reacted at a high temperature of 280 to 310 ° C. for a long time, 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, Japanese Patent Publication No. 61-39972 and Japanese Patent Laid-Open No.
Japanese Patent Laid-Open No. 3-223036 discloses a method of using a specific catalyst. Also, JP-A-61-15123
No. 6, JP-A-62-158719 and the like disclose a method of adding an antioxidant in the latter stage of the reaction.
In JP-A-61-62522 and the like, a twin-screw vent type kneading extruder is disclosed in the latter stage of the reaction, and in JP-A-2-15.
Japanese Patent No. 3925 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. 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 using a specific metal material as the inner wall material of the 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 metal nitride or a metal carbide is used as an inner wall material of a reactor for carrying out the transesterification reaction. The present invention provides a method for manufacturing the same.

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 (for example, methylene group, ethylene group, propylene group, butylene group, penterylene group, hexylene group, ethylidene group, isopropylidene group). Ridene group, etc.), C5-15
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-1-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, for example 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-methyldiethanolamine; 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. By using the adduct as described above, bisphenol A having high purity can be obtained, which is effective.

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; Formula

[0042]

[Chemical 17]

2,5-dicumylphenol represented by:
3,5-dicumylphenol; as a chroman derivative,
For example, the expression

[0044]

[Chemical 18]

Examples thereof include monohydric phenols. Of these phenols, although not particularly limited in the present invention, p-tert-butylphenol; p-cumylphenol; p-phenylphenol 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.

The production method of the present invention comprises the above-mentioned component (A),
When a polycarbonate is produced by a transesterification reaction using a terminal terminating agent, a branching agent or the like as the component (B) and other components, a metal nitride or a metal carbide is used as an inner wall material of a reactor for carrying out the transesterification reaction. The major feature is to provide these coatings.
Here, there are various reactors for carrying out the transesterification reaction, which may be appropriately selected and used depending on the situation. In the present invention, it is necessary to coat the inner wall of this reactor with a metal nitride or a metal carbide. When the transesterification reaction is carried out without providing the above-mentioned coating on the inner wall of the reactor, a polycarbonate which is inferior in hydrolysis resistance and retention burn and inferior in color tone is obtained. In the present invention, the surface of the inner wall of the reactor (particularly, the inner wall with which the raw material components or the produced polymer comes into contact) may be coated with the material made of the above metal nitride or metal carbide. To the contacting parts such as the piping part, auxiliary equipment or extruder.
Providing a coating of metal nitride or metal carbide is more effective. Examples of these auxiliary devices and the like include, for example, stirring blades and shafts equipped in the reactor, instrumentation parts such as temperature sensors, pipe parts or pipe members (for example, flanges) adjacent to the reactor, or extruders. Examples include cylinders and screws.

In the present invention, the metal nitride used for the inner wall material of the reactor is, for example, Be ₃ N _3.
2 , Mg ₃ N ₂ , LaN, TiN, ZrN, HfN, T
Examples include aN, Cr ₂ N, WN, MnN and the like. Of these, TiN is particularly preferably used. Also,
Specific examples of the metal carbide include Be ₂ C, YC ₂ ,
LaC ₂ , CeC ₂ , UC, TiC, ZrC, NbC,
TaC, Cr ₂₃ C ₆ , WC and the like can be mentioned. Of these, TiC is particularly preferably used. These metal nitrides or metal carbides are usually formed on the inner wall of the reactor,
It is provided as a film. Various methods can be adopted as a method of providing the metal nitride or metal carbide coating on the reactor. For example, known methods such as a chemical vapor deposition method, a physical vapor deposition method, a molten salt method, and a thermal spraying method can be mentioned.
Among these, the chemical vapor deposition method is preferable, and the particularly preferable method is the ion plating method.

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, the reactor coated with the metal nitride or metal carbide, for example, in the laboratory, in an autoclave provided with a coating of metal nitride or metal carbide on the inner wall, first,
After charging the dihydroxy compound of the component (A) and the carbonic acid diester of the component (B) in a ratio such that the carbonic acid diester is 1 to 1.5 times the mol of the dihydroxy compound,
The usual transesterification reaction occurs. 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 is 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 can be separated, purified and recycled for use, and it is preferable to have a facility for removing them. 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 obtained as described above 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, it is effective when used in combination with polyphenylene ether, polyether nitrile, terminal-modified polysiloxane compound, modified polypropylene, modified polystyrene or the like having an OH group, COOH group, NH ₂ group or the like at the end.

[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 Bisphenol A was placed in an autoclave (with a stirrer) provided with a titanium nitride coating film having an internal volume of 1,400 ml.
228 g (1.00 mol) of (BPA) and 257 g (1.2 mol) of diphenyl carbonate were charged, 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 (1 × 10 ⁻⁵ ) of (C ₄ H ₉ ) ₄ NBH ₄ was used.
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 at the same time, the produced phenol started to be distilled off. The reaction was held at 220 ° C for 1 hour. After that, gradually increase the temperature from 220 ° C to 280 ° C by 1
At the same time as the temperature was raised, the degree of vacuum was raised to remove the residual diphenyl carbonate and to proceed with the transesterification reaction. Finally, with the pressure kept at 0.5 torr, the reaction was carried out by stirring for 1 hour, and finally a viscous and transparent condensate (PC) was obtained in the autoclave. The viscous and transparent condensate obtained was dissolved in methylene chloride and the viscosity average molecular weight was measured. As a result, it was 22,300. Further, the viscous and transparent condensate obtained is crushed and
Pelletized at 70 ° C. The obtained pellets were press-molded, and the press plate (thickness 3 mm) was subjected to YI, hydrolysis resistance and retention burn test.

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 repeated except that a nickel steel autoclave was used in place of the titanium nitride-coated autoclave. Comparative Example 2 The procedure of Example 1 was repeated, except that an autoclave made of SUS316L was used instead of the autoclave provided with the titanium nitride film.

PC (viscous and transparent condensate) obtained in Examples and Comparative Examples was dissolved in methylene chloride, and the viscosity average molecular weight was measured. In addition, the PCs obtained in Examples and Comparative Examples
Was crushed and pelletized at 270 ° C. using an extruder.
The obtained pellets are press-molded and pressed into a plate (thickness: 3 m
m) was tested for YI, hydrolysis resistance and retention burn test. Table 1 shows the measurement results of the viscosity average molecular weight and the results of YI, hydrolysis resistance and retention burn test.

[0061]

[Table 1]

The viscosity average molecular weight, YI, hydrolysis resistance 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) Hydrolysis resistance The state after the press plate (thickness 3 mm) was exposed to 121 ° C. steam for 48 hours was visually observed. 4) 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 metal nitride or a metal carbide as an inner wall material of a reactor for carrying out a transesterification reaction, there is no deterioration of the hydrolysis resistance, and there is no quality of retention burn. It is possible to produce a polycarbonate having excellent color tone (transparency) as well as excellent heat resistance. Therefore, the present invention can be effectively and widely used as a method for industrially producing a polycarbonate by a 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, a metal nitride or a metal carbide is used as an inner wall material of a reactor for carrying out the transesterification reaction. A method for producing a polycarbonate, comprising: