JP3334723B2 - Method for producing polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a novel method for producing polycarbonate. More specifically, in the transesterification method, a production method in which an inert gas is supplied in the first reaction zone and the second reaction zone to perform a transesterification reaction to efficiently obtain a polycarbonate excellent in hue and mechanical strength. It is about.

[0002]

2. Description of the Related Art Polycarbonate resins are excellent in mechanical strength such as heat resistance and impact resistance, transparency, etc., and are used as engineering plastics, for example, optical components, mechanical components, electric / electronic devices. It is used in various fields such as parts, automobile parts, and various containers. As a method for producing a polycarbonate resin having such properties, an interfacial polycondensation method, a solution method,
A transesterification method and the like are known. Among them, the interfacial polycondensation method and the solution method use phosgene,
There is a problem that methylene chloride used as a solvent remains. On the other hand, the transesterification method does not have the above problems, but has a mechanical problem because the transesterification reaction is performed at a high temperature. At the same time, the problem that phenol generated by transesterification must be removed,
There is a problem that the quality tends to deteriorate due to high temperature. Hitherto, various studies have been made to solve the problems in the method for producing a polycarbonate by the transesterification method. For example, Japanese Patent Publication No. 52-36159,
JP-A-86618, JP-A-2-153923, and the like disclose an improved technique from the type of device. Further, Japanese Patent Application Laid-Open No. Hei 4-72327 discloses an improved technique for the material of the device. Further, Japanese Unexamined Patent Application Publication No.
JP-A-158033 and JP-A-3-59028 disclose:
Although a solid phase polymerization method for preventing quality deterioration due to high temperature is also disclosed, it requires a crystallization operation, has a low reaction rate, and has a problem in productivity. In the transesterification method, a high vacuum is required to remove the phenol produced, and the operation becomes industrially very difficult. Further, the incorporation of air cannot be completely prevented, and tends to cause coloring due to oxidative deterioration. For this reason, a contrivance has been made to solve the problem of coloring by using nitrogen gas in the reaction system.

[0003]

In view of the above situation, the present inventors have solved the problems of the conventional transesterification method and have been able to efficiently produce a polycarbonate excellent in hue and mechanical strength. We worked diligently to develop a method. As a result, by changing the reaction temperature of the first reaction zone and the second reaction zone, the inert gas is supplied not only for the purpose of oxygen removal but also continuously or intermittently, and the transesterification reaction proceeds. It has been found that polycarbonate having desired physical properties can be efficiently produced. The present invention has been made based on such findings. That is, in the present invention, in the first reaction zone, the (A) divalent hydroxy compound and the (B) carbonate compound are reacted at a reaction temperature of 100 to 280 ° C. 0.01-20 (weight ratio), and subjected to a transesterification reaction to give a viscosity average molecular weight of 1,000.
A reaction mixture comprising ~ 25,000 low molecular weight polycarbonate is formed, and then in a second reaction zone, the reaction temperature of the reaction mixture is higher than in the first reaction zone and 200
At ~ 350 ° C, an inert gas is supplied to the divalent hydroxy compound in an amount of 0.0002 to 10 (weight ratio), and the ester exchange reaction is carried out to obtain a viscosity average molecular weight of 10,000 to 50,000.
It is intended to provide a method for producing a polycarbonate, characterized by producing the above polycarbonate.

First, in the present invention, there are various types of the divalent hydroxy compound as the component (A). For example, an aromatic dihydroxy compound or an aliphatic dihydroxy compound can be used. For example, as the aromatic dihydroxy compound, usually, a compound represented by the general formula (I)

[0005]

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[0006] wherein, R ¹ and R ² are each a halogen atom (e.g., chlorine, bromine, fluorine, iodine) or an alkyl group having 1 to 8 carbon atoms, if the R ¹ and R ² are a plurality of And they may be the same or different, and m and n are each an integer of 0 to 4. X
Is a single bond, an alkylene group having 1 to 8 carbon atoms,
8, an alkylidene group having 5 to 15 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or -S
—, —SO—, —SO ₂ —, —O—, —CO— bond or the general formula (II)

[0007]

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(Where R^ThreeAnd R^FourIs the hydrogen source
Or a monovalent hydrocarbon group, ^FiveIs divalent hydrocarbon
Elementary group. ). ]
Compounds. Represented by the above general formula (I)
There are various compounds, and in particular, 2,2-
Bis (4-hydroxyphenyl) propane [commonly known as bis
Phenol A] is preferred. Other than bisphenol A
As the aromatic dihydroxy compound, for example, bis (4
-Hydroxyphenyl) methane; 1,1-bis (4-h
Droxyphenyl) ethane; 2,2-bis (4-hydro
2,2-bis (4-hydroxy)
Phenyl) octane; 2,2-bis (4-hydroxyf
Enyl) phenylmethane; 2,2-bis (4-hydroxy
Bis-1-methylphenyl) propane; bis (4-hydro
1-bis (4-phenyl) naphthylmethane;
(Doxy-t-butylphenyl) propane; 2,2-bi
(4-hydroxy-3-bromophenyl) propane;
2,2-bis (4-hydroxy-3,5-tetramethyl
Phenyl) propane; 2,2-bis (4-hydroxy-
3-chlorophenyl) propane; 2,2-bis (4-h
Droxy-3,5-tetrachlorophenyl) propane;
2,2-bis (4-hydroxy-3,5-tetrabromo
Bis (hydroxyaryl) a such as phenyl) propane
Lucans, 1,1-bis (4-hydroxyphenyl) cy
Clopentane; 1,1-bis (4-hydroxyphenyl)
L) cyclohexane; 1,1-bis (4-hydroxy
Enyl) -3,5,5-trimethylcyclohexane and the like
Bis (hydroxyaryl) cycloalkanes, 4,
4'-dihydroxyphenyl ether; 4,4'-dihi
Dioxy-3,3'-dimethylphenyl ether
Hydroxyaryl ethers, 4,4'-dihydroxy
Sidiphenyl sulfide; 4,4'-dihydroxy-
Dihydro such as 3,3'-dimethyldiphenyl sulfide
Xydiaryl sulfides, 4,4'-dihydroxy
> Diphenylsulfoxide; 4,4'-dihydroxy-
Dihydrides such as 3,3'-dimethyldiphenylsulfoxide
Roxydiaryl sulfoxides, 4,4'-dihydro
Xydiphenyl sulfone; 4,4'-dihydroxy-
Dihydroxy such as 3,3'-dimethyldiphenylsulfone
Sidiaryl sulfones, 4,4'-dihydroxydife
Dihydroxydiphenyls such as nil;
You. Also, the aromatic dihydroxy represented by the general formula (I)
Hydroquinone, resorcinol,
Dihydroxybenzenes such as tylhydroquinone;
Ethoxylated or propoxylated products of nol, such as
For example, bis-oxyethyl-bisphenol A;
Xyethyl-tetrachlorobisphenol A; bis-o
Xyethyl-tetrachlorohydroquinone, 1,5-dihi
Droxynaphthalene; 2,6-dihydroxynaphthalene
And dihydroxynaphthalenes.

There are various kinds of aliphatic dihydroxy compounds. 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; ethoxylation of 2,2-bis- (4-hydroxycyclohexyl) -propane and a dihydric alcohol or And propoxylation products.

In the present invention, the divalent hydroxy compound is represented by any of the general formulas (III) to (VI)

[0011]

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[In the formula, Ar ₁ represents a residue obtained by removing two hydroxyl groups from an aromatic dihydroxy compound. R is
A residue obtained by removing two hydroxyl groups from an aliphatic dihydroxy compound is shown. R ⁶ represents an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group having 4 to 7 carbon atoms. And the like. Bissules of an aromatic dihydroxy compound, bissuls of an aliphatic dihydroxy compound, carbonates of an aromatic dihydroxy compound, carbonates of an aliphatic dihydroxy compound, and the like can also be used. These divalent hydroxy compounds may be used alone or in combination of two or more.

On the other hand, in the present invention, there are various carbonate compounds as the component (B).
A diaryl carbonate compound represented by the general formula (VII),
Dialkyl carbonate compound represented by (VIII), or a general formula
It is an alkylaryl carbonate compound represented by (IX). Here, the general formulas (VII) to (IX) are represented as follows.

[0014]

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Wherein R ⁶ is as defined above, and Ar ₂
Represents an aryl group. Examples of the diaryl carbonate compound represented by the general formula (VII) include diphenyl carbonate, ditolyl carbonate, m-cresyl carbonate, dinaphthyl carbonate, and bis (diphenyl) carbonate. In addition, the above general formula (V
Examples of the dialkyl carbonate compound represented by III) include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, and the like. And, as the alkylaryl carbonate compound represented by the general formula (IX), for example, methylphenyl carbonate, ethylphenyl carbonate, butylphenyl carbonate, cyclohexylphenyl carbonate and the like can be mentioned. These carbonate compounds may be used alone or in combination of two or more.

In the present invention, in carrying out the transesterification reaction using the divalent hydroxy compound and the carbonate compound, a transesterification catalyst is not always necessary, but is preferably used. Here, examples of the transesterification catalyst include simple substances of alkali metals or alkaline earth metals, oxides, hydroxides, amide compounds, alcoholates, phenolates, ZnO, PbO,
Basic metal compounds such as Sb ₂ O ₃ , organic titanium compounds, soluble manganese compounds, Ca, Mg, Zn, Pb,
Examples of the catalyst include a combined catalyst of Sn, Mn, Cd, Co acetate or a nitrogen-containing basic compound and a boron compound, and a nitrogen-containing basic compound, an alkali (earth) metal compound and a boron compound. Further, a solid catalyst containing an ion exchange resin or an inorganic ion exchanger may be used. These catalysts may be used alone or in combination of two or more. The amount of the catalyst to be used is generally 0 to 10 ^-1 mol, preferably 0 to 10 ^-2 mol, relative to the divalent hydroxy compound. This usage is 10 ^-1
If the molar ratio is exceeded, the catalyst remaining in the polymer deteriorates quality and adversely affects mechanical properties.

Further, in the present invention, although not particularly limited, various compounds which are usually used for polymerization of polycarbonate can be used as a terminal terminator. Specific examples of the terminal stopper include monohydric phenols such as phenol, on-butylphenol, mn-butylphenol, pn-butylphenol, o-isobutylphenol, m-isobutylphenol and p-butylphenol. -Isobutylphenol, ot-butylphenol, mt-butylphenol, pt-butylphenol, on-pentylphenol, mn
-Pentylphenol, pn-pentylphenol,
on-hexylphenol, mn-hexylphenol, pn-hexylphenol, pt-octylphenol, o-cyclohexylphenol, m-cyclohexylphenol, p-cyclohexylphenol, o-phenylphenol, m-phenyl Phenol, p-phenylphenol, on-nonylphenol, m-nonylphenol, pn-nonylphenol, o-cumylphenol, m-cumylphenol, p
-Cumylphenol, o-naphthylphenol, m-naphthylphenol, p-naphthylphenol;
2,4-di-t-butylphenol; 3,5-di-t-butylphenol; 2,5
-Dicumylphenol; 3,5-dicumylphenol;
p-cresol, bromophenol, tribromophenol and the like. In addition, formula (IV)

[0018]

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And the like. These monohydric phenols may be used alone or in combination of two or more. And among these monohydric phenols, pt-butylphenol, p-cumylphenol, p-phenylphenol and the like are preferably used. Other branching agents include, for example, 1,1,1-tris (4-hydroxyphenyl) ethane; α, α ′, α ″ -tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene; -[Α-methyl-α- (4′-hydroxyphenyl) ethyl] -4- [α ′, α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene; phloroglysin, trimellitic acid, isatin bis (o-cresol ), Etc., compounds having three or more functional groups can also be used.

Further, as another terminal stopper, a carbonic acid diester compound can be used depending on the situation. Examples of such a terminal terminator for a carbonic acid diester compound include carboxybutiphenylphenyl carbonate,
Methylphenyl butyl phenyl carbonate, ethyl phenyl butyl phenyl carbonate, dibutyl diphenyl carbonate, biphenyl phenyl carbonate, dibiphenyl carbonate, walmi phenyl phenyl carbonate, diculmi phenyl carbonate, naphthyl phenyl phenyl carbonate, dinaphthyl phenyl carbonate, carboxypropoxy phenyl carbonate, carbonate Heptoxyphenyl carbonate, carbomethoxy-t-butylphenylphenyl carbonate, carboprotoxyf, nilmethylf, nilphenyl carbonate, chromanylphenyl carbonate, dichromanyl carbonate, and the like.

In the production method of the present invention, the divalent hydroxy compound and the carbonate compound are used, and if necessary, the above-mentioned terminal terminator or catalyst is blended to obtain a polycarbonate by a transesterification method. The exchange reaction is characterized in that the reaction temperature is changed between the first reaction zone and the second reaction zone and the inert gas is supplied continuously or intermittently to advance the reaction. That is, in the transesterification reaction, the raw materials (A) as the aromatic dihydroxy compound, the aliphatic dihydroxy compound,
A divalent hydroxy compound which is a bisester of an aromatic dihydroxy compound, a bisester of an aliphatic dihydroxy compound, a carbonate of an aromatic dihydroxy compound, or a carbonate of an aliphatic dihydroxy compound; and (B) a diaryl carbonate compound, The carbonate compound, which is a dialkyl compound or an alkyl carbonate compound, is mixed with the divalent hydroxy compound so that the carbonate compound becomes 1 to 1.5 times by mole. Depending on the situation, the amount of the carbonate compound is
A little excess to the divalent hydroxy compound
The molar ratio is preferably 1.02 to 1.20 times. In the transesterification reaction, the viscosity is low in the initial stage and the viscosity increases in the second half,
In the present invention, the reaction is allowed to proceed in the first reaction zone and the second reaction zone or more using apparatuses suitable for each. In this case, in the first reaction zone, a usual stirring tank or horizontal stirrer can be used. In the second reaction zone, a horizontal single-shaft or twin-shaft stirrer or a self-cleaning type thereof can be used. Furthermore, it is effective to provide a vacuum flash tank in the second reaction zone so that phenol by-produced during or at the end of the reaction can be removed.

In the present invention, the divalent hydroxy compound and the carbonate compound are blended as described above, and are dissolved at a reaction temperature of 100 to 280 ° C. in the first reaction zone. Next, an inert gas was added to the divalent hydroxy compound at 0.
The mixture is fed at a ratio of 01 to 2 (weight ratio) and transesterified to form a reaction mixture containing a low-molecular-weight polycarbonate. Here, the dissolution and reaction of each raw material may be performed in the same device, or may be performed in separate devices. Also,
The method of supplying the inert gas is not particularly limited, and may be performed at the time of dissolving the raw materials. If the reaction temperature is lower than 100 ° C., the reaction rate becomes slow, and if it exceeds 280 ° C., side reactions such as deterioration tend to occur, which is not preferable.
Phenol by-produced in the transesterification reaction is removed at normal pressure, increased pressure, or reduced pressure under an inert gas flow. In the continuous transesterification process, a distillation column is preferably provided above or outside the reactor in order to return the entrained raw materials to the reactor.

In the transesterification reaction, the reaction proceeds by continuously or intermittently supplying an inert gas. The amount of the inert gas is supplied according to the amount of phenol produced as a by-product. As described above, the amount of the inert gas is 0.01 to 20 (weight ratio) with respect to the divalent hydroxy compound.
And transesterified. If the amount of the inert gas is less than 0.01 (weight / weight), phenol as a by-product cannot be sufficiently removed. On the other hand, if the amount of the inert gas exceeds 20 (weight / weight), the amount of the inert gas with respect to the phenol to be recovered increases, making recovery difficult. The supplied inert gas has an oxygen concentration in the inert gas of 10 ppm or less, preferably 2 ppm or less,
More preferably, those having a concentration of 0.2 ppm or less are used.
When supplying this inert gas, the pressure is usually -500
The pressure may be from mmHg to 10 kg / cm ² (gauge pressure) . In the present invention, examples of the inert gas include N ₂ , H
Although e, Ar, Ne, CO _{2 and the} like can be used, N ₂ is most advantageous industrially. The transesterification in the first reaction zone may be a continuous process or a batch process. In this transesterification reaction, if necessary, the reactor can be divided into two or more according to the conditions of the apparatus (temperature, pressure, etc.). Thus, in the first reaction zone, a reaction mixture containing a low molecular weight polycarbonate having a viscosity average molecular weight of 1,000 to 25,000 is produced by the transesterification reaction. Here, when the viscosity average molecular weight is less than 1,000, the reaction load in the next second reaction zone becomes large, and when it exceeds 25,000, the viscosity becomes too high and it is difficult to treat with a normal stirrer. Becomes

Next, in the production method of the present invention, in the second reaction zone, the reaction mixture formed in the first reaction zone is heated to a temperature higher than the reaction temperature in the first reaction zone and from 200 to 35.
In the range of 0 ° C., the inert gas is supplied in a ratio of 0.002 to 1 (weight ratio) with respect to the divalent hydroxy compound,
The target polycarbonate can be obtained by transesterification. When the transesterification reaction is performed in the second reaction zone, the reaction temperature is higher than 100 to 280 ° C, which is the reaction temperature in the first reaction zone, and is in the range of 200 to 350 ° C. If the reaction temperature in the second reaction zone is lower than 200 ° C., the viscosity is too high to make transesterification difficult, and if it exceeds 350 ° C., the quality is deteriorated by side reactions and the like, which is not preferable. And also in the second reaction zone, in the transesterification reaction, the inert gas is used for the divalent hydroxy compound,
It is supplied at a ratio of 0.002 to 10 (weight ratio), and is subjected to transesterification. Here, if the amount of the inert gas is less than 0.002 (weight / weight), phenol by-produced cannot be sufficiently removed. When the inert gas amount is 10 (weight /
), It becomes difficult to collect the entrained by-product phenol.

The by-product phenol entrained in the inert gas in the second reaction zone is condensed by a condenser,
Alternatively, it is recovered by a normal recovery method such as an adsorption method,
Can be reused. After removing the by-product phenol, the inert gas can be reused in the transesterification in the first reaction zone. The pressure in the second reaction zone is usually from -500 mmHg to 10 kg / cm ² (Ga
Di pressure), preferably -300mmHg~5kg / cm ²
(Gauge pressure) . This pressure is -500 mmHg (
If the pressure is less than (pressure) , the cost of the vacuum apparatus is high, and leakage from equipment such as oxygen may increase.
On the other hand, if it exceeds 10 kg / cm ² (gauge pressure) , the cost of the apparatus is undesirably increased. The transesterification in the second reaction zone may be a continuous process or a batch process. In this transesterification reaction, the type of the reactor is not limited as long as it has a normal stirring function, but since the viscosity increases from the first reaction zone, a high-viscosity type stirring is performed. Those having functions are preferred. For these, a single-screw or twin-screw horizontal stirrer or a usual extruder can be used. By subjecting the reaction mixture thus formed in the first reaction zone to a transesterification reaction in the second reaction zone, the viscosity average molecular weight becomes 10,
000-50,000 polycarbonate can be obtained. Then, the obtained polycarbonate is granulated as it is, or granulated after adding various additives, and is appropriately provided for molding of a desired molded product.

In addition, in the production method of the present invention, the first reaction zone and the second reaction zone are not strictly distinguished, but are set so that the reaction can be performed efficiently. For this reason, the reaction temperature of the second reaction zone is usually set higher than the reaction temperature of the first reaction zone, as described above. As a result, in the first reaction zone, the addition ratio of the divalent hydroxy compound is usually 4 to 99%, and in the second reaction zone, it is 40 to 100%.
%. The first reaction zone and the second reaction zone may have two steps or more depending on the conditions. Then, the transesterification time in the present invention may be performed until the target molecular weight is reached, and is usually 0.2 to 10 hours. In addition, in the transesterification reaction, if necessary, all the steps of the reaction or the subsequent steps (second reaction zone)
An antioxidant can be used. Examples of the antioxidant include tris (nonylphenyl) phosphite, trisphenyl phosphite, 2-ethylhexyldiphenyl phosphite, trimethyl phosphite,
Triethyl phosphite, tricresyl phosphite,
And phosphorus-based antioxidants such as triaryl phosphite. Furthermore, the N ₂ supplied to each reaction zone
Such an inert gas may be supplied as it is, but it is preferable to heat the reaction gas before and after the reaction temperature in advance in order to prevent the reaction temperature from lowering, in order to promote the reaction efficiently.

In the manufacturing method of the present invention, the effect of supplying the inert gas is not clear, but the following reasons are considered. That is, by being contained in the inert gas or the melt, the apparent viscosity is reduced, and the reaction can proceed promptly. In addition, since the number of gas-phase interfaces increases and by-products can be efficiently removed, reactivity can be improved. And the latter stage of the reaction (second reaction zone)
It is presumed that since no ultra-high vacuum (0.01 to 1 torr) is required, air leakage and the like can be almost completely eliminated. To show an outline of an example of the production method of the present invention,
As shown in FIG.

[0028]

The present invention will be further described with reference to Examples and Comparative Examples.
explain in detail. Example 1 An autoclave (with a helical stirring blade) made of stainless steel (SUS316) having an internal volume of 1.4 liters was charged with 228 g (1 mol) of bisphenol A and 257 g (1.2 mol) of diphenyl carbonate (diphenyl carbonate).
After sufficiently purging with nitrogen gas, the mixture was heated to 180 ° C. and dissolved. Next, the temperature was raised from 180 ° C. to 220 ° C., and simultaneously, nitrogen gas was supplied at 800 ml / min (1 g).
/ Min). The temperature of the nitrogen gas was increased to 220 ° C. by a heating coil in an oil path. Soon after, it was confirmed by analysis that phenol was present in the nitrogen gas extracted from the upper part of the autoclave. In this state, a transesterification reaction was performed for about 2.5 hours to form a reaction mixture. The viscosity average molecular weight of the polycarbonate produced from this reaction mixture was 2,200.
And a low molecular weight polycarbonate. Then 220
Temperature from 280 ° C to 50 ° C while nitrogen gas
Continuous blowing was carried out at 0 ml / min (about 0.63 g / min) to advance the transesterification reaction. This reaction is performed in 3.5
After a period of time, a viscous and transparent polycarbonate was obtained in the autoclave. The obtained polycarbonate was dissolved in methylene chloride, and the viscosity average molecular weight was measured. As a result, the viscosity average molecular weight of this polycarbonate was 22,500. The obtained polycarbonate was pulverized, and 220 to 27
The mixture was granulated and pelletized at 0 ° C. with an extruder. The pellets were injection-molded, and the obtained molded product was subjected to YI (Yellowness Index).
x) and hot water tensile strength were measured. The obtained result is the third
It is shown in the table.

Examples 2 to 7 and Comparative Examples 1 to 4
The procedure was performed in the same manner as in Example 1 except that the values were changed according to Tables and Table 2. Table 3 shows the obtained results. The measurement of the viscosity average molecular weight, YI and hot water tensile strength was performed according to the following. 1) Viscosity average molecular weight (Mv) The viscosity of the methylene chloride solution at 20 ° C. was measured with an Ubbelohde type viscosity tube, and the intrinsic viscosity [η] deciliter / g was determined from this. [Η] = 1.23 × 10 ⁻⁵ Mv ^0.83 2) YI (Yellowness Index) Measured according to JIS K-7103-77 using a color meter SM-3 (manufactured by Suga Test Instruments Co., Ltd.). 3) Tensile strength in hot water After immersion in hot water of 80 ° C for 16 hours, JIS after 2 hours
It measured according to K-7113-81.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

Example 8 228 g (1 mol) of bisphenol A, 257 g (1.2 mol) of diphenyl carbonate, diphenyl ether 2
Example 1 was repeated except that 8.2 g (0.17 mol, 10% by weight) and 6.8 g of p-cumylphenol (0.05 mol based on bisphenol A) were used as a terminator.
Was performed in the same manner as described above. The viscosity average molecular weight of the polycarbonate produced in the first reaction zone was 1,800, a low molecular weight polycarbonate. Finally, the viscosity-average molecular weight of the viscous and transparent polycarbonate remaining in the autoclave was measured in the same manner, and it was found to be 20,500.

Example 9 228 g (1 mol) of bisphenol A, 257 g (1.2 mol) of diphenyl carbonate, diphenyl ether 2
8.2 g (0.17 mol, 10% by weight) and as a catalyst 0.018 g of boric acid, 0.18 g of a 15% aqueous solution of tetramethylammonium hydroxide and 0.18 g of sodium hydrogen carbonate.
The same operation as in Example 1 was carried out except that 003 g was charged. The viscosity average molecular weight of the polycarbonate produced in the first reaction zone was 2,100, a low molecular weight polycarbonate. Finally, the viscosity-average molecular weight of the viscous and transparent polycarbonate remaining in the autoclave was measured in the same manner, and it was 24,000.

Comparative Example 5 The same operation as in Example 8 was carried out except that the amount of N ₂ used in the second reaction zone was changed. The viscosity average molecular weight of the polycarbonate produced in the first reaction zone was 650, which was a low molecular weight polycarbonate. The viscosity average molecular weight of the obtained polycarbonate was measured in the same manner, and it was 9,200.

Example 10 4,000 g of bisphenol A was charged into a stainless steel (SUS316) autoclave (with an anchor-type stirring blade) having an internal volume of 15 liters, purged sufficiently with nitrogen gas, and heated to 180 ° C. Dissolved. Separately, 8,000 g of diphenyl carbonate was charged into another autoclave of the same size, sufficiently purged with nitrogen gas, and heated to 180 ° C. to dissolve. Each of the above raw materials was continuously supplied to a stainless steel (SUS316) autoclave (with a helical stirring blade) having an internal volume of 5 liters by a small gear pump. The feed rate was 342 g / h for bisphenol A and 1,1 for diphenyl carbonate.
It was fed at 885 g / h. At the same time, nitrogen gas
It was fed from the bottom of the autoclave at a rate of 0 ml / min (1.51 g / min). The autoclave was heated to 220 ° C. Nitrogen gas at 220 ° C
Heated. Continuously withdraw the mixture from the bottom so that the residence time in the autoclave is about 3 hours,
KRC Kneader [Kurimoto Iron Works Co., Ltd., (2inch, L /
D = 12, 1.2 liters), and a transesterification reaction was performed in the first reaction zone to produce a reaction mixture. The jacket was heated to 240 ° C., and nitrogen gas was supplied to the mixture supply section at 750 ml / min, and the gas was discharged from the vent near the discharge port. The viscosity average molecular weight of the polycarbonate produced in the first reaction zone was 2,800, a low molecular weight polycarbonate. Next, the obtained reaction mixture was supplied to a KRC kneader having the same size as described above, and similarly, nitrogen gas was supplied at a rate of 750 ml / min to perform a transesterification reaction. In addition, KRC
The kneader was heated to 280 ° C. About the obtained polycarbonate, the result of similarly measuring the viscosity average molecular weight,
It was 19,300.

Tables 4 and 5 show the reaction conditions in Examples 8 to 10 and Comparative Example 5, such as the amount of the monomer and nitrogen gas and the reaction time. Further, the polycarbonates obtained in Examples 8 to 10 and Comparative Example 5 were molded in the same manner as in Example 1, and the molded product was subjected to YI (Yellowness I).
ndex) and hot water tensile strength. Table 6 shows the results.

[0039]

[Table 5]

[0040]

[Table 6]

[0041]

[Table 7]

[0042]

As described above, according to the present invention, the divalent hydroxy compound and the carbonate compound are used, the reaction temperature in the first reaction zone and the reaction temperature in the second reaction zone are changed, and an inert gas is supplied to carry out an esl exchange reaction. , Polycarbonate can be easily obtained. The polycarbonate obtained by the production method of the present invention is excellent in hue and mechanical strength, and is suitably used for optical parts, mechanical parts, electric / electronic parts, automobile parts and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one example of a production method of the present invention.

[Explanation of symbols]

A: BPA dissolving tank, B: DPC dissolving tank, C: First reaction tank, D: Heat exchanger (for nitrogen gas of first reaction), E: Monomer recovery device, F: Second reaction tank,
G: heat exchanger (for nitrogen gas in the second reaction), H: monomer recovery device, J: first reaction tank, K: heat exchanger (for nitrogen gas in the third reaction), L: granulation device, 1 : BPA,
2: DPC, 3: nitrogen gas (for first reaction), 4: nitrogen gas (for second reaction), 5: nitrogen gas (for third reaction)

────────────────────────────────────────────────── ─── Continued from the front page Examiner Satoshi Morikawa (56) References JP-A-1-158303 (JP, A) JP-A-64-4617 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C08G 64/00-64/42

Claims (3)

(57) [Claims] In the first reaction zone, (A) a divalent hydroxy compound and (B) a carbonate compound are reacted at a reaction temperature of 100 to 100.
At 280 ° C., and supplying an inert gas to the divalent hydroxy compound at a rate of 0.01 to 20 (weight ratio),
After transesterification, the viscosity average molecular weight becomes 1,000-2.
A reaction mixture containing 5,000 low molecular weight polycarbonates is formed, then in a second reaction zone the reaction temperature of the reaction mixture is higher than in the first reaction zone and between 200 and 3
At 50 ° C., an inert gas is supplied to the divalent hydroxy compound at a ratio of 0.002 to 10 (weight ratio) and transesterified to give a viscosity average molecular weight of 10,000 to 50,0.0.
A method for producing a polycarbonate, comprising producing the polycarbonate of No. 00. 2. The method according to claim 1, wherein the oxygen concentration in the inert gas used in the first reaction zone and the second reaction zone is 10 ppm or less. 3. The pressure in the first reaction zone and the second reaction zone is -500 mmHg / cm ² (gauge pressure). The method for producing a polycarbonate according to claim 1, wherein: