JPH07247350A - Production of polycarbonate - Google Patents

Abstract

PURPOSE:To produce a polycarbonate of excellent quality at good efficiency while increasing the molecular weight within a short time and reducing the amount of residual low-molecular-weight substances by transesterifying a dihydroxy compound with a carbonic diester in the presence of a blowing agent. CONSTITUTION:The process for producing a polycarbonate from a dihydroxy compound and a carbonic diester by transesterification, comprises performing the reaction in the presence of a blowing agent. In this process, it is desirable that the initial decomposition temperature of the blowing temperature is 150-350 deg.C, and that the amount of the blowing agent added is 0.00001-0.5pt.wt. per pt.wt. dihydroxy compound as the starting material. According to the above process, the deaeration of the formed phenol can be accelerated, the molecular weight can be therefore increased within a short time, the amount of residual low-molecular-weight substances can be reduced, and a polycarbonate of excellent quality can be produced at good efficiency.

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, a high molecular weight can be obtained in a short time by a transesterification reaction in the presence of a foaming agent, and a low molecular weight substance (raw material) The present invention relates to a method for efficiently producing a high-quality polycarbonate that can reduce the amount of residual monomer).

[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 polycondensation) 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. When PC is produced by the transesterification method, the transesterification reaction is an equilibrium reaction, so that the by-produced phenols can be efficiently removed.
It is an important factor for improving the reaction rate, particularly for obtaining a high-molecular weight PC. However, since the high molecular weight PC melt has a high viscosity, operations such as stirring are difficult, and it is not easy to remove phenols from the high molecular weight PC melt, and the reaction requires a long time. Generally, in the high viscosity region, a horizontal twin-screw vent type kneading extruder (for example, JP-A-61-262) is used.
No. 522), a horizontal stirring polymerization tank (for example, JP-A-2-
No. 175722) is used, but these devices have a problem that they are expensive. Further, the effect of shortening the reaction time is not sufficient, and there is a problem that the resin is easily deteriorated due to mechanical shearing due to an operation such as stirring while being exposed to a high temperature for a long time. A large amount of low molecular weight substances (bisphenol A, diphenyl carbonate, etc.) remain in the finally obtained PC, and in such a case, there is a drawback that a problem such as die attachment during molding tends to occur. As a technique for solving this drawback, there is also a method of improving the reaction rate by lowering the viscosity in the system by using a solvent and promoting the diffusion and deaeration of the produced phenols (JP-A-4-202221). However, there is a problem that equipment such as solvent recovery is required. Further, a high vacuum is required to remove the produced phenols, and there is also a problem that equipment for this is required.

[0003]

In view of the above situation, the present inventor has solved the drawbacks of the above-mentioned conventional method and, by the transesterification method, have a high molecular weight and an excellent P quality.
We have conducted intensive studies to develop a method for efficiently producing C. As a result, when PC is produced by the transesterification method, a defoaming reaction of the phenols produced is promoted by causing a transesterification reaction in the presence of a foaming agent, preferably a foaming agent that decomposes and foams at a certain temperature or higher. It is possible to improve the speed and increase the molecular weight in a short time, and reduce the residual amount of low molecular weight substances.
It has been found that problems such as die attachment can be solved and the object of the present invention can be achieved. The present invention has been completed based on such findings. That is, the present invention is
The present invention provides a method for producing a polycarbonate, which comprises subjecting a polycarbonate from a dihydroxy compound (A) and a carbonic acid diester (B) by a transesterification method to a transesterification reaction in the presence of a foaming agent.

First, 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)

[0005]

[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 ')

[0007]

[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) -3,3,5-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)

[0011]

[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 7 carbon atoms.
Represents a cycloalkyl group having a ] The compound represented by the general formula (IV)

[0013]

[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)

[0015]

[Chemical 5]

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

[0017]

[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)

[0019]

[Chemical 7]

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

[0021]

[Chemical 8]

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

[0023]

[Chemical 9]

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

[0025]

[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, but these may be used alone or in combination of two or more. Of these, bisphenol A (BPA), which is an aromatic dihydroxy compound, is preferably used. And
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, various kinds of carbonic acid diesters are used as the component (B). For example, it is at least one compound selected from a diaryl carbonate compound, a dialkyl carbonate compound or an alkylaryl carbonate compound. The diaryl carbonate compound used as one of the components (B) has the general formula (XI)

[0028]

[Chemical 11]

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

[0030]

[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)

[0032]

[Chemical 13]

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

[0034]

[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)

[0036]

[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)

[0038]

[Chemical 16]

[In the formula, R ² , Ar ¹ and Ar ² are the same as described 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. In the present invention, as the carbonic acid diester of the component (B), the above compounds are appropriately selected and used, and among these, diphenyl carbonate (DPC) is preferably used. These carbonic acid diesters may be used alone or in combination of two or more.

In the production method of the present invention, a polycarbonate is obtained 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 o-n-butylphenol; m-n-butylphenol; pn-butylphenol; o-isobutylphenol; m-isobutylphenol; p-isobutylphenol; ot-butylphenol. M-
t-butylphenol; pt-butylphenol; o
-N-pentylphenol; m-n-pentylphenol; p-n-pentylphenol; o-n-hexylphenol; m-n-hexylphenol; p-n-hexylphenol; o-cyclohexylphenol; m-
P-Cyclohexylphenol; p-cyclohexylphenol; o-phenylphenol; m-phenylphenol; p-phenylphenol; o-n-nonylphenol; m-n-nonylphenol; p-n-nonylphenol; o-cumylphenol; Millphenol;
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

[0041]

[Chemical 17]

Examples of the compound represented by

[0043]

[Chemical 18]

Examples include monohydric phenols such as 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

[0045]

[Chemical 19]

Examples thereof include compounds represented by Furthermore
In the present invention, if necessary, for example, as a branching agent,
For example, phloroglucin; trimellitic acid; 1,1,1-to
Lis (4-hydroxyphenyl) ethane; 1- [α-me
Cyl-α- (4'-hydroxyphenyl) ethyl] -4
-[Α ', α'-bis (4 "-hydroxyphenyl) e
Cyl] benzene; α, α ′, α ″ -tris (4-hydro)
Xyphenyl) -1,3,5-triisopropylbenze
3 or more functional groups such as isatin bis (o-cresol)
The compounds having the above can also be used. Also in the present invention
Does not require a catalyst, but promotes transesterification
Known catalysts may be used to drive the reaction. like this
Specific examples of the catalyst include alkali metal or alkaline earth.
Simple metals, oxides, hydroxides, amide compounds, al
Corrate, phenolate, or ZnO, PbO, S
b₂O₃Basic metal oxides, such as organic titanium compounds
Substance, soluble manganese compound, Ca, Mg, Zn, Pb,
Sn, Mn, Cd, Co acetate or nitrogen-containing basification
Compound and boron compound, nitrogen-containing basic compound and alkali (earth
Type) metal compounds, nitrogen-containing basic compounds and alkalis (earth
) A combination catalyst such as a metal compound and a boron compound is listed.
You can The amount of these catalysts used should be
0 to 10 relative to the compound ^-1Mol, preferably 0
-10^-2It can be used in the molar range. Its use
Quantity 10^-1If it exceeds the molar amount, the catalyst remains in the polymer.
May adversely affect quality and mechanical properties.

The production method of the present invention comprises:
When a polycarbonate is produced by a transesterification reaction by using a terminal terminating agent, a branching agent or the like as the component (B) and optionally other components, a major feature is that the foaming agent is allowed to coexist in the transesterification reaction. There are various foaming agents that can be used in the present invention. It is preferable to use a thermally decomposable organic compound that decomposes and foams when heated to a certain temperature or higher and generates a gas without leaving a decomposition residue in the polymer. Degradable foaming agents of this type are usually
Those that generate gas such as nitrogen, carbon dioxide, carbon monoxide, ammonia, oxygen, hydrogen, etc., and those that generate a large amount of gas are preferably used. Examples thereof include a tetrazole compound, a triazole compound, a hydrazine compound, a semicarbazide compound, an azo compound, an azide, and a nitroso compound. And the decomposition start temperature of the above-mentioned preferable foaming agent is 150 to 350 ° C, preferably 180 to 350 ° C.
The temperature is 300 ° C, more preferably 210 to 280 ° C. When the decomposition initiation temperature is lower than 150 ° C, the effect of the foaming agent may be lost before the transesterification reaction proceeds substantially. On the other hand, if the temperature exceeds 350 ° C, the foaming agent is not decomposed during the polymerization and the effect is not exhibited, and in some cases, the polymer may be thermally deteriorated, which is not preferable. Then, in the above preferable range, the effect of improving the molecular weight in a short time and reducing the low molecular weight substance can be obtained.

Among the foaming agents, examples of the tetrazole compound include 1H-tetrazole; 5-phenyl-
1H-tetrazole; 5,5'-bi-1H-tetrazole;5-methyl-1H-tetrazole; 1-methyl5-
Ethyl-1H-tetrazole; 5-amino-1H-tetrazole; 1-methyl5-mercapto-1H-tetrazole; 5 (2-aminophenyl) -1H-tetrazole; 1-cyclohexyl-5-mercapto-1H-tetrazole, etc. Further, salts of these tetrazoles with amines such as ammonia, triethylamine, ethylenediamine, pyridine and guanidine can be mentioned. Further, as the triazole compound, for example, 1H
-1,2,4-triazole; 2H-1,2,3-triazole; 4H-1,2,4-triazole and the like. And as the hydrazine compound, for example,
Examples thereof include p, p'-oxybis (benzenesulfonylhydrazide) and trihydrazinotriazine. Examples of the semicarbazide compound include p-toluenesulfonyl semicarbazide.

Furthermore, examples of the azo compound include azodicarbonamide, barium azodicarboxylate, hydrazodicarbonamide, and isopropyl hydrazodicarboxylate. Moreover, examples of the nitroso compound include N, N′-dinitrosopentamethylenetetramine. The foaming agents may be used alone or in combination of two or more kinds.

When the transesterification reaction is carried out using the components (A) and (B) as the main components, the foaming agent is (A)
It is 0.000 per part by weight of the component dihydroxy compound.
It is added in a proportion of 01 to 0.5 parts by weight, preferably 0.0005 to 0.05 parts by weight, more preferably 0.0001 to 0.01 parts by weight. If the amount of the compound of this foaming agent is less than 0.0001 parts by weight, the effect aimed at by the present invention may not be exhibited. On the other hand, if it exceeds 0.5 parts by weight, the effect is not exhibited in the ratio of addition, which leads to an increase in cost, which is not preferable. Then, in the above preferable range, the effect of improving the molecular weight can be obtained in a short time, and the effect of reducing the low molecular weight substance in the polymer can be obtained. In the present invention, the timing of adding the foaming agent is not particularly limited and may be added at the same time as the raw material monomers, or at any time before the viscosity average molecular weight of the polymer reaches the desired molecular weight. Good. In particular, it is preferable to add the polymer at a time when the viscosity average molecular weight of the polymer is 30000 or less, preferably 20000 or less, more preferably 15,000 or less, and the temperature of the reaction system is not higher than the decomposition initiation temperature of the foaming agent.

In the production method of the present invention, specifically, the reaction may be carried out under the above-mentioned conditions according to a known transesterification method. The procedure and conditions of the production method of the present invention will be specifically described below. First, the dihydroxy compound as the component (A) and the carbonic acid diester as the component (B) are 0.9 to 1.5 times mol, preferably 0.95 to 1.25 times mol of the carbonic acid diester to 1 mol of the dihydroxy compound. Mol, more preferably
After charging at a ratio of 1.0 to 1.2 times the molar amount,
A predetermined amount of a foaming agent is added to the dihydroxy compound as the component (A) to carry out a normal transesterification reaction. Alternatively, after charging the dihydroxy compound of the component (A) and the carbonic acid diester of the component (B) in the above ratio, a normal transesterification reaction is carried out, and the viscosity average molecular weight of the polymer before the desired molecular weight is obtained. At the time of, the transesterification reaction is performed. In the above transesterification reaction,
When the amount of the terminal stopper composed of the monohydric phenol or the like is in the range of 0.05 mol% to 10 mol% with respect to 1 mol of the dihydroxy compound as the component (A), hydroxyl groups of the obtained polycarbonate are Since the ends are sealed, a polycarbonate having 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,
Usually 100 ° C to 350 ° C, preferably 180 ° C to 330
℃, more preferably gradually as the reaction progresses 18
It is preferable to raise the temperature from 0 ° C to 300 ° C. 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, the atmospheric pressure (normal pressure) up to 1 to 50 atm (760 to 38,000 torr) or the pressurized state is kept, and in the latter stage of the reaction, the reduced pressure state, preferably finally 0.01 ~ 1
Often set to 0 torr. When the reaction is allowed to proceed under atmospheric pressure (normal pressure) or pressure, an inert gas (eg, nitrogen, argon, etc.) may be passed. Further, the reaction time may be such that it reaches a predetermined molecular weight, but the progress thereof is faster than that of a normal transesterification reaction, and it is usually about 0.2 to 9 hours.

Further, in the present invention, if necessary,
The antioxidant can be used during polymerization or after reaching a predetermined viscosity average molecular weight. The antioxidant is not particularly limited, but specific examples of the phosphorus-based antioxidant include tris (nonylphenyl) phosphite [eg, TNP manufactured by Sumitomo Chemical Co., Ltd.], diphenylmono (2 -Ethylhexyl) phosphite [Johoku Chemical Co., Ltd.
Manufactured by EPB], trisphenylphosphite, 2-ethylhexyldiphenylphosphite, tris (2,4-
Di-tert-butylphenyl) phosphite [Ciba-Geigy company make, Irgafos 168], trimethyl phosphite, triethyl phosphite, tricresyl phosphite, triaryl phosphite, etc. are mentioned.

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 material and structure of the reactor used in the present invention are not particularly limited, but it is sufficient that the reactor has 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, but when using a foaming agent having a high foaming effect, a tank reactor or the like may be used.

The PC thus obtained may be granulated as it is, or may be molded by using an extruder or the like. 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. The obtained PC is a polyolefin, polystyrene, polyester, polysulfonate, polyamide,
It is possible to blend with polymers such as polyphenylene oxide. In particular, 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, it is effective in improving the physical properties.

[0056]

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 (BPA) was applied to an ampoule having an inner diameter of 12 mm.
0.228 g (0.001 mol), diphenyl carbonate (diphenyl carbonate: DPC) 0.225 g (0.000015)
Mole), 5-phenyltetrazole 0.46 mg, tetramethylammonium hydroxide 9.1 μg (1 × 10 ⁻⁷⁾
Mol) was added, and nitrogen substitution was performed 5 times. The ampoule was placed in an oil bath at 180 ° C., and the degree of vacuum was gradually raised from 200 torr to 1 torr in 40 minutes. Then
It was put in an oil bath at 290 ° C. while being kept at 1 torr. Foaming occurred as the internal temperature rose. After reacting for 30 minutes as it was, a sample was taken out.

Example 2 In Example 1, without adding 5-phenyltetrazole from the beginning, the temperature was gradually increased from 200 torr at 180 ° C. to 1 t.
The degree of vacuum was raised to orr in 40 minutes to advance the reaction. Then, the ampoule tube was re-pressurized with nitrogen, and 0.46 mg of 5-phenyltetrazole was added and mixed. 1 torr
After the pressure was reduced to, the mixture was placed in an oil bath at 290 ° C., and the same procedure as in Example 1 was performed.

Example 3 Example 3 was repeated except that 0.7 mg of 5,5'-bi-1H-tetrazole diammonium salt (C ₂ H ₈ N ₁₀ ) was used in place of 5-phenyltetrazole. It carried out like Example 2. Example 4 The diammonium salt of 5,5′-bi-1H-tetrazole in place of 5-phenyltetrazole in Example 2 is used.
Example 2 was repeated except that 0.23 mg was used. Example 5 The procedure of Example 2 was repeated, except that 0.7 mg of barium azodicarboxylate was used instead of 5-phenyltetrazole.

Example 6 In Example 1, the reaction was performed at 240 ° C. for 90 minutes without using tetramethylammonium hydroxide, and then 1
The vacuum degree was gradually raised to torr in 30 minutes. After the pressure of the ampoule tube was released by recompression, the diammonium salt of 5,5′-bi-1H-tetrazole (1.12 mg) was added and mixed, and the same procedure as in Example 2 was performed.

Comparative Example 1 The procedure of Example 1 was repeated except that 5-phenyltetrazole was not used. Comparative Example 2 Example 1 was repeated except that 5-phenyltetrazole was not used and the reaction was carried out at 290 ° C. and 0.5 torr for 90 minutes. Comparative Example 3 The procedure of Example 1 was repeated, except that azobisisobutyronitrile was used instead of 5-phenyltetrazole. Comparative Example 4 The procedure of Example 6 was repeated, except that the diammonium salt of 5,5′-bi-1H-tetrazole was not used.

The foaming agents, reaction conditions, etc. of Examples 1 to 6 and Comparative Examples 1 to 4 are as shown in Table 1. The viscosity average molecular weight (M
v) and residual low molecular weight substances in the polymer were measured. The results are shown in Table 2. The viscosity average molecular weight (Mv)
And the measurement of residual low molecular weight substances in the polymer was 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) Residual low molecular weight substance After dissolving the polymer in methylene chloride, acetonitrile is added to concentrate the polymer, and the polymer is removed. And diphenyl carbonate were quantified. Column: FINPACK SILC18 Mobile phase: Acetonitrile-water 65/35

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

[0065]

As described above, according to the present invention, when a polycarbonate is produced from a dihydroxy compound and a carbonic acid diester by a transesterification reaction method, a defoaming agent coexists in the presence of a foaming agent to remove the produced phenols. Thus, it is possible to increase the molecular weight in a short period of time, reduce the residual amount of low-molecular weight substances, and efficiently produce a polycarbonate of excellent quality. Therefore, the present invention can be effectively and widely used as a method for industrially producing a polycarbonate by a transesterification method.

Claims (3)

[Claims] 1. A method for producing a polycarbonate, which comprises producing a polycarbonate from (A) a dihydroxy compound and (B) a carbonic acid diester by a transesterification method, and causing a transesterification reaction in the presence of a foaming agent. 2. The decomposition starting temperature of the foaming agent is 150 to 35.
It is 0 degreeC, The manufacturing method of the polycarbonate of Claim 1 characterized by the above-mentioned. 3. The method for producing a polycarbonate according to claim 1, wherein the amount of the foaming agent added is 0.0001 to 0.5 part by weight relative to 1 part by weight of the starting dihydroxy compound.