JP3197416B2 - Manufacturing method of aromatic polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an aromatic polycarbonate.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used because they have excellent mechanical properties such as impact resistance, and also have excellent heat resistance and transparency. As a method for producing an aromatic polycarbonate, a method in which an aromatic dihydroxy compound such as bisphenol A is directly reacted with phosgene (interfacial method), or an ester exchange between an aromatic dihydroxy compound such as bisphenol A and a carbonic acid diester such as diphenyl carbonate is used. A method of performing a reaction (polycondensation reaction) and the like are known. The former method is currently generally practiced, but the latter method is considered to be promising because it does not use cumbersome compounds such as phosgene.

[0003] Generally, bisphenol A (melting point 156)
C.) and diphenyl carbonate (melting point 80 ° C.) separately or mixed and heated and melted. After adding a catalyst to a mixed solution of both compounds, the mixture is heated to the reaction temperature and polycondensed in a reactor.

[0004] In general, when polycarbonate is used for optical applications or precision parts, foreign substances such as dust, dust and gel in the polymer are removed through a filter.

[0005] Since polycarbonate obtained by the interfacial method using phosgene is usually taken out in the form of a powder, it must be re-melted using an extruder, and foreign substances must be removed through a filter.

On the other hand, polycarbonate obtained by a polycondensation reaction using an aromatic dihydroxy compound and a carbonic acid diester is taken out in a molten state after completion of the polycondensation, and thus has the advantage that foreign substances can be removed through a filter as it is.

However, in the continuous process of polycarbonate by the polycondensation reaction, filter clogging occurs in a short period of time, and the filter must be replaced frequently.
There is a drawback that stable operation cannot be performed for a long time.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to stably produce an aromatic polycarbonate having an excellent hue and containing few foreign substances for a long period of time.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for producing an aromatic polycarbonate by melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester using at least two reactors in series. A method comprising providing at least one filter at each of the outlet of the final reactor before the reactor and at the end of the final reactor.

That is, the present inventors have found that the coloring substance formed in the reactor in the polycondensation step has a relatively large particle size, and the substance causing coloring having a relatively small particle size is an aromatic dihydroxy compound or carbonate. It was discovered that it was caused by foreign substances such as dirt and dust contained in raw materials such as diester. Therefore, first, the present invention removes the fine particles by high-precision filtration before the final reactor in which the viscosity of the polymer is relatively low, and removes the colored substances generated in the reactor by coarse filtration in the final stage in which the polymer viscosity is high. It was completed.

As described above, in the method of the present invention, high-precision filtration is performed before the final reactor having a relatively low viscosity, and coarse filtration is performed in the final stage having a higher viscosity. It is possible to stably produce a polycarbonate having excellent hue and very few foreign substances over a long period of time.

In the case where all foreign substances are removed only by the filter at the outlet of the final reactor, clogging of the filter at the outlet of the final reactor occurs in a short period of time, and the filter must be replaced frequently. During replacement of the filter, the polymer must be drawn out of the apparatus before the filter or the operation must be stopped, so that stable operation cannot be ensured for a long period of time. It is also conceivable to provide two or more filters at the outlet of the final reactor in parallel and operate them alternately. However, since there is no choice but to branch the pipe or use a plurality of pipes, it is not possible to avoid the stagnation of the polymer with the usual design, and the polymer is liable to be colored or deteriorated.

The filter used in the present invention comprises:
It may be a commonly used type such as a flat type, a cylinder type, a candle type and the like. The absolute filtration accuracy of the filter installed before the final reactor is preferably 0.5 μm or more and 5 μm or less. If the absolute filtration accuracy exceeds 5 μm, impurities contained in the raw material aromatic dihydroxy compound and carbonic acid diester,
In addition, the fine particles caused by the catalyst and the stabilizer cannot be completely removed, and foreign matter increases in the generated aromatic polycarbonate, which is not preferable. The filter is provided at least one before the final reactor.

When the filter before the final reactor is clogged and replaced, the supply of the raw material is stopped. At this time, the operation after the filter can be continued by using the polymer from which the foreign substances in the raw materials have been removed and accumulated in each reactor, and the filter is replaced during that time. Does not cause any trouble. In addition, since the polymer viscosity is low before the final reactor, and it is difficult to form a staying place, two or more filters can be installed in parallel and used alternately.

The absolute filtration accuracy of the filter at the outlet of the final reactor is preferably more than 5 μm and not more than 30 μm. When the absolute filtration accuracy exceeds 30 μm, it is not preferable because it is not possible to remove a polymer deterioration or the like which may cause coloring during the reaction. On the other hand, if the absolute filtration accuracy is 5 μm or less, the filter is clogged and polycarbonate cannot be stably produced for a long time, which is not preferable. The filter is provided with at least one filter at the outlet of the final reactor.

As described above, at least two filters are arranged in series with one or more reactors separated. The arrangement can be appropriately determined according to the type or number of reactors, polymerization conditions, and the like. Absent. For example, an arrangement in which a filter with the highest absolute filtration accuracy is installed at the inlet of the first reactor, a filter is installed at the outlet of each subsequent reactor, and a filter with a low absolute filtration accuracy is sequentially installed as the polymer viscosity increases. Is mentioned.

The polymerization reaction of the present invention proceeds in the presence of a catalyst. As the catalyst, preferably described in JP-A-2-124
Those known in JP-A-934 and JP-A-60-51719 are used. When the above-mentioned catalyst is used, the particle size which causes the deterioration of the polymer in the polycondensation stage is 10
There is no generation of gel fine particles of about μm or less. Therefore,
In the final stage where the polymer viscosity is high, the particle size generated near the gas-liquid interface of the reactor is only 1 by coarse filtration.
The above object of the present invention can be completely achieved only by removing large polymer carbides exceeding 0 μm.

Examples of the above-mentioned catalyst include a catalyst comprising (a) a nitrogen-containing basic compound and (b) an alkali metal compound or an alkaline earth metal compound.

Here, (a) the nitrogen-containing basic compound includes, for example, tetramethylammonium hydroxide (M
e ₄ NOH, where Me represents a methyl group. Hereinafter, the ethyl group may be abbreviated to Et, the butyl group to Bu, and the phenyl group to Ph. ), Tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), trimethylbenzylammonium hydroxide _{(C 6 H 5 -CH 2 (} Me) 3 NO
H), such as ammonium hydroxides having an alkyl, aryl, or araryl group; tertiary amines such as trimethylamine, triethylamine, dimethylbenzylamine, and triphenylamine; R ₂ NH (R ₂ NH)
Is an alkyl group such as methyl and ethyl, an aryl group such as phenyl and toluyl, etc.), a primary amine represented by RNH ₂ (where R is the same as described above), or ammonia , Tetramethylammonium borohydride (Me ₄ NBH ₄ ), tetrabutylammonium borohydride (Bu ₄ NB
Basic salts such as H ₄ ), tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ), and tetramethylammonium tetraphenylborate (Me ₄ NBPh ₄ ) are used.

Of these, tetraalkylammonium hydroxides are particularly preferred.

(B) As the alkali metal compound, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, acetic acid Potassium, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, Dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt, dipotassium salt, dilithium salt of bisphenol A, sodium salt, potassium salt and lithium salt of phenol are used.

Examples of the alkaline earth metal compound (b) include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, and calcium carbonate. , Barium carbonate,
Magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate and the like are used.

The nitrogen-containing basic compound (a) is used in an amount of 10 ^{-6 based on} 1 mole of the aromatic dihydroxy compound.
In an amount of from 10 ^-1 to ¹ mol, preferably from 10 ^-5 to 10 ^-2 mol, and (b) the alkali metal compound or alkaline earth metal compound is from 10 ^-8 to 10 ^-3 mol, preferably from 10 ^-7 to 10 ^-4. It is particularly preferably used in a molar amount of 10 ^-7 to 10 ^-5 mol.

(A) When the amount of the nitrogen-containing basic compound is 10 ^-6 to 10 ^-1 mol per 1 mol of the aromatic dihydroxy compound, the transesterification reaction and the polymerization reaction proceed at a sufficient rate, Further, it is preferable in that a polycarbonate excellent in hue, heat resistance and water resistance can be obtained.

When the amount of (b) the alkali metal compound or the alkaline earth metal compound is 10 ^-8 to 10 ^-3 mol per 1 mol of the aromatic dihydroxy compound, the polymerization activity can be increased, Further, it is preferable in that a polycarbonate excellent in hue, heat resistance and water resistance can be obtained.

As described above, the catalyst obtained by combining (a) the nitrogen-containing basic compound and (b) the alkali metal compound or the alkaline earth metal compound has a high polymerization activity and can produce a high-molecular-weight polycarbonate. The polycarbonate obtained is excellent in heat resistance and water resistance, and furthermore has an improved color tone and excellent transparency.

Secondly, a catalyst comprising (a) a nitrogen-containing basic compound, (b) an alkali metal compound or an alkaline earth metal compound, and (c) boric acid or a borate ester can be mentioned.

Here, as (a) a nitrogen-containing basic compound and (b) an alkali metal compound or an alkaline earth metal compound, the same compounds as described above are used.

(C) As boric acid or boric acid ester, boric acid or a general formula B (OR) _n (OH) _3-n (where R is an alkyl group such as methyl and ethyl, and an aryl group such as phenyl) And n is 1, 2 or 3)
Is used.

Examples of such borate esters include trimethyl borate, triethyl borate, tributyl borate, trihexyl borate, triheptyl borate, triphenyl borate, tritolyl borate, and trinaphthyl borate.

The nitrogen-containing basic compound (a) is used in an amount of 10 ^{-6 based on} 1 mole of the aromatic dihydroxy compound.
In an amount of from 10 ^-1 to ¹ mol, preferably from 10 ^-5 to 10 ^-2 mol, and (b) the alkali metal compound or alkaline earth metal compound is from 10 ^-8 to 10 ^-3 mol, preferably from 10 ^-7 to 10 ^-4. Particularly preferably in an amount of 10 ^-7 to 10 ^-5 mol, and (c) the boric acid or borate is 10 ^-8 to 10 ^-1
It is preferably used in an amount of 10 ^-7 to 10 ^-2 mol, particularly preferably 10 ^-6 to 10 ^-4 mol.

(A) When the amount of the nitrogen-containing basic compound is 10 ^-6 to 10 ^-1 mol per 1 mol of the aromatic dihydroxy compound, the transesterification reaction and the polymerization reaction proceed at a sufficient rate, Further, it is preferable in that a polycarbonate excellent in color tone, heat resistance and water resistance can be obtained.

(B) When the amount of the alkali metal compound or alkaline earth metal compound is from 10 ^-8 to 10 ^-3 mol per 1 mol of the aromatic dihydroxy compound, the polymerization rate can be increased, and It is preferable in that a polycarbonate excellent in color tone, heat resistance and water resistance can be obtained.

(C) The amount of boric acid or boric acid ester is from 10 ^-8 to 1 mol per mole of the aromatic dihydroxy compound.
When the amount is 10 ^-1 mol, a decrease in molecular weight after thermal aging hardly occurs, and a polycarbonate excellent in color tone, heat resistance and water resistance can be obtained.

As described above, a catalyst obtained by combining (a) a nitrogen-containing basic compound, (b) an alkali metal compound or an alkaline earth metal compound, and (c) boric acid or a borate ester has a higher polymerization activity. Thus, a polycarbonate having a high molecular weight can be produced, and the obtained polycarbonate is further excellent in heat resistance and water resistance, further improved in color tone, and excellent in transparency.

Third, (a) Formula (R ¹ ) ₄ NOH (wherein each R ¹ is independently an alkyl group having 1 to 4 carbon atoms or 6 to 6 carbon atoms)
At least one quaternary ammonium hydroxide having 10 aryl or aralkyl groups; and (b) a formula (R ² O) ₃ B, wherein each R ² is independently a lower alkyl group or a formula X _n Ar ¹ (Ar ¹ is an aromatic hydrocarbon group having 6 to 10 carbon atoms, each X is independently an electron-withdrawing substituent, and n is 0 to A
catalysts comprising at least one borate ester having a group which is the number of substitutable aromatic carbon atoms in r ¹ ).

Here, (a) in the formula (R ¹ ) ₄ NOH, each R ¹ is an alkyl group having 1 to 4 carbon atoms (eg, methyl, ethyl, n-propyl, isopropyl, n-butyl) or 6 carbon atoms. 10 to 10 aryl or aralkyl groups (eg, phenyl, benzyl). Most often, all R ¹ are the same and are alkyl, especially methyl or ethyl, preferably methyl. Tetramethylammonium hydroxide is particularly preferred. (B) formula (R ² O) ₃ B is an alkyl, aryl or mixed alkyl - a arylboronic acid ester. In the formula, any of R ² can be independently a lower alkyl group, that is, an alkyl group having up to 7 carbon atoms. Preferably they have 1 to 4 carbon atoms. Examples of the alkyl group include methyl, ethyl, butyl, hexyl and heptyl, and includes all isomers, but a normal compound is preferred.

Any or all of R ² are phenyl,
It may be an aromatic hydrocarbon group such as tolyl, xylyl or naphthyl (same as Ar ¹ above). The Ar ¹ group contains ^one or more electron-withdrawing X substituents such as nitro, halo (especially chloro), alkanoyl (eg, acetyl), carboalkoxy (eg, carbomethoxy) and trifluoromethyl. The number of substituents is indicated by the subscript suffix n, the highest value being the number of substitutable aromatic carbon atoms in Ar ¹ (eg 5 for phenyl, 7 for naphthyl). Usually n is 0, 1 or 2, if it is 1 or 2, the substituent is preferably in the ortho or para position relative to the boron atom. The value of n is preferably 0 or 1, most preferably 0.

(B) As the borate ester of the formula (R ² O) ₃ B, tri-n-butyl borate and triphenyl borate are preferred.

As the reactor used in the present invention, any known reactor can be used, and any of a continuous system, a semi-continuous system or a batch system can be used, but a continuous system is preferable. In general, different stirring modes of the reactor are used for the pre-polymerization stage where the viscosity of the reaction system is low and the post-polymerization stage where the viscosity is high.

Examples of the reactor include a vertical stirring polymerization tank, a thin-film evaporation polymerization tank, a vacuum chamber polymerization tank, a horizontal stirring polymerization tank,
Examples include a twin-screw vented extruder, and two or more of these reactors can be used in combination in series. Preferred is a combination in which two or more reactors are used in series and at least one reactor is a horizontal reactor such as a horizontal stirred polymerization tank. As the combination, for example, a vertical stirring polymerization tank and a horizontal stirring polymerization tank, a horizontal stirring polymerization tank and a vertical stirring polymerization tank, a horizontal stirring polymerization tank and a horizontal stirring polymerization tank, a vertical stirring polymerization tank and a vacuum chamber polymerization tank. A horizontal stirring polymerization tank, a thin film evaporation polymerization tank and two horizontal stirring polymerization tanks, and the like can be given. In particular, a combination in which three or more reactors are used in series and at least one reactor is a horizontal reactor such as a horizontal stirred polymerization tank is preferable, for example, two or more vertical stirred polymerization tanks and one Horizontal stirring polymerization tank, one or more vertical stirring polymerization tanks, one thin film evaporation polymerization tank and one horizontal stirring polymerization tank, or one or more vertical stirring polymerization tanks and two or more horizontal stirring polymerization tanks Matching. As described above, the polymerization reaction can be efficiently performed by using at least two reactors in series.

In the present invention, the aromatic dihydroxy compound has the following formula [I]

[0043]

Embedded image (Where X is

[0044]

Embedded image -O -, - S -, - SO- or -SO ₂ -,
R ₁ and R ₂ are a hydrogen atom or a monovalent hydrocarbon group, and R ₃ is a divalent hydrocarbon group. The aromatic nucleus may have a monovalent hydrocarbon group. ).

As such an aromatic dihydroxy compound,
For example, bis (4-hydroxyphenyl) methane, 1,1
-Bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-3-t-butylphenyl) Bis (hydroxyaryl) alkanes such as propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4- Bis (hydroxyaryl) cycloalkanes such as (hydroxyphenyl) cyclohexane, dihydroxyaryl ethers such as 4,4′-dihydroxydiphenylether and 4,4′-dihydroxy-3,3′-dimethylphenylether;
4,4'-dihydroxydiphenyl sulfide, 4,4
Dihydroxydiaryl sulfides such as'-dihydroxy-3,3'-dimethyldiphenylsulfide;
4,4'-dihydroxydiphenylsulfoxide, 4,
Dihydroxydiarylsulfoxides such as 4'-dihydroxy-3,3'-dimethylphenylsulfoxide;4,4'-dihydroxydiphenylsulfone;
Examples include dihydroxydiarylsulfones such as 4'-dihydroxy-3,3'-dimethyldiphenylsulfone, and 2,2-bis (4-hydroxyphenyl) propane (so-called bisphenol A) is particularly preferred.

The carbonic diester can be, for example, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. And diphenyl carbonate is particularly preferred.

The above-mentioned carbonic acid diester may contain a dicarboxylic acid or a dicarboxylic acid ester in an amount of preferably 50 mol% or less, more preferably 30 mol% or less. Examples of the dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When a dicarboxylic acid or a dicarboxylic acid ester is used in combination with a carbonic acid diester, a polyester polycarbonate is obtained.

The carbonic acid diester is used in an amount of 0.90 to 1.30 mol, preferably 0.95 to 1.20 mol, per 1 mol of the aromatic dihydroxy compound. A compound having three or more functional groups (preferably a phenolic hydroxyl group or a carboxyl group) in one molecule can be further added, and preferably 0.001 to 0.03 mol, particularly 0 to 1 mol of the aromatic dihydroxy compound. It is used in an amount of 0.001 to 0.01 mol. Examples of such compounds are described in JP-A-4-89824.

In the polymerization reaction, various phenols can be used as a terminal blocking agent.
No. 175723 can be mentioned.

Also, in the present invention, ordinary heat stabilizers, ultraviolet absorbers, release agents, coloring agents, antistatic agents, slip agents, antiblocking agents, lubricants, antifogging agents, natural oils, synthetic oils, waxes Also, organic fillers, inorganic fillers and the like can be added.

FIG. 1 shows an example of an apparatus for implementing the method of the present invention.
Shown in The stirring tank 4 has stirring blades attached to a vertical rotation shaft, and continuously supplies the above-mentioned aromatic dihydroxy compound and carbonic acid diester through the pipes 1 and 2, respectively. The stirring tank atmosphere is substantially free of oxygen, and the stirring tank is purged with, for example, nitrogen gas. A catalyst is supplied to the stirring tank through a pipe 3 and mixed with the reaction raw materials. A plurality of stirring tanks can be provided in series to form a uniform solution.

The mixed raw material is supplied to a filter 15 having an absolute filtration accuracy of 0.5 μm or more and 5 μm or less through a pipe 6 by a pump 5, and then to a prepolymerization tank 8. The prepolymerization tank is a vertical stirring polymerization tank, and is provided with a stirring blade having a vertical rotation axis. The inside of the tank is kept at a reduced pressure by a vent conduit 7 provided at the top. By-product phenol and some unreacted monomer sucked through the conduit 7 are respectively rectified, phenol is discharged out of the system, and unreacted monomer is returned to the polymerization tank. Further, a catalyst can be further supplied through the pipe 3 '.

The polymerization product in the pre-polymerization tank 8 is supplied to a gear pump 9
Through the pipe 10 to the filter 16 having an absolute filtration accuracy of 0.5 μm or more and 5 μm or less. One or more combinations of the prepolymerization tank 8 and the filter 16 can be provided in a series, and preferably two to four are provided,
The more downstream, the more stringent the reaction conditions. The reaction temperature in the first prepolymerization tank is usually 50 to 270 ° C, preferably 1 to
The temperature is in the range of 50 to 260 ° C and the pressure is 6 m from normal pressure.
The pressure can be reduced to mHg, and the lower limit is preferably 4
00 to 6 mmHg, particularly preferably 300 to 6 mmHg
Can be set in the range.

The reaction temperature in the second and subsequent prepolymerization tanks is usually 180 to 285 ° C, preferably 200 to 270 ° C.
° C and the pressure is in the range of 1 to 50 mmHg, preferably 1 to 30 mmHg.

The aromatic polycarbonate having a certain degree of polymerization as described above has an intrinsic viscosity [η] of 0.1 to 0.5 dl / measured in a methylene chloride solution at 20 ° C.
g, preferably 0.15 to 0.45 dl / g, and more preferably 0.15 to 0.4 dl / g.

Next, the polymerization product was placed in a horizontal stirring polymerization tank 1.
2 is supplied. One or two horizontal stirring polymerization tanks
It has at least two horizontal rotating shafts, and one or two or more stirring blades such as a disk type, a wheel type, a paddle type, a rod type, and a window frame type are combined with the horizontal rotating shaft, and at least 2
This is a horizontal high-viscosity liquid processing apparatus that is installed in stages and lifts or spreads the reaction solution by the stirring blades to renew the surface of the reaction solution. The reaction temperature there is usually 240
To 320 ° C., preferably 250 to 290 ° C., and the pressure is 4 mmHg or less, preferably 2 mmHg.
It is as follows.

The polymerization product in the horizontal stirring polymerization tank 12 passes through a pipe 14 by a gear pump 13 and has an absolute filtration accuracy of 5%.
It is supplied to a filter 17 having a size of more than 30 μm and exceeding μm.

As for the combination of the horizontal stirring polymerization tank 12 and the filter 17, at least one, preferably one or two, is provided in series. When two are provided in series, the absolute filtration accuracy of only the filter installed at the outlet of the last horizontal stirring polymerization tank is set to be more than 5 μm and 30 μm or less.
The viscous polymer was taken out of the bottom of the last horizontal stirring polymerization tank through a filter by a gear pump,
The intrinsic viscosity [η] measured in a methylene chloride solution at 0 ° C. is 0.20 to 1.0 dl / g, preferably 0.30 to 0.1 dl / g.
9 dl / g, more preferably 0.33 to 0.8 dl / g
Is obtained. After the polycondensation reaction is performed in the last horizontal stirring polymerization tank, the reaction can be further performed by a twin-screw vented extruder. In the case of using a twin-screw vented extruder, the polycondensation reaction has progressed considerably in the horizontal stirring polymerization tank at the preceding stage, so the reaction conditions of the twin-screw vented extruder can be relaxed and the quality of polycarbonate is prevented from deteriorating. It is possible to do. In this case, the twin-screw vent type extruder is preferably installed between the gear pump 13 and the filter 17. Further, after the polycondensation is completed, it is also possible to guide the resin to an extruder while the resin is in a molten state, and knead the stabilizer and the filler. The extruder may be any of those usually used, and may be single-screw or twin-screw, and may or may not have a vent. Also in this case, the extruder is preferably installed between the gear pump 13 and the filter 17.

FIG. 2 shows an example of an apparatus in which two vertical stirring polymerization tanks, one centrifugal thin film evaporation polymerization tank, and one horizontal stirring polymerization tank are combined. An aromatic dihydroxy compound and a carbonic acid diester are placed in a stirring tank 31 under a nitrogen purge, respectively.
Continuously supplied from 2, 33, and sufficiently stirred and mixed. Multiple stirring tanks can be provided in series to form a uniform solution.

The mixed raw material is supplied to a pipe 3 by a pump 53.
4 and supplied to a filter 47 having an absolute filtration accuracy of 0.5 μm or more and 5 μm or less.
Supplied to The prepolymerization tank is a vertical stirring polymerization tank, and is provided with a stirring blade having a vertical rotation axis.

A catalyst is continuously supplied to the pre-polymerization tank 35 via a pipe 36. The prepolymerization tank 35 is controlled at a temperature and a pressure suitable for starting the transesterification reaction, for example, 50 to 270 ° C., preferably 150 to 2 ° C.
At a temperature of 60 ° C., a pressure from normal pressure to 6 mmHg. The reaction mixture is then discharged from the prepolymerization tank 35, supplied to a filter 48 having an absolute filtration accuracy of 0.5 μm or more and 5 μm or less through a pipe 37 by a pump 54, and then transferred to a prepolymerization tank 38. In the middle of the pipe 37, a catalyst can be further added via a pipe 36 '.

The prepolymerization tank 38 has a temperature suitable for the polycondensation reaction,
Controlled by pressure. For example, at a temperature of 50 to 270 ° C, preferably 150 to 260 ° C, and 6 mmH
The pressure is reduced to g. In the pre-polymerization tank 38, the intrinsic viscosity [η] (measured with a methylene chloride solution at 20 ° C.)
0.4 dl / g of polycarbonate is obtained.

Next, the absolute filtration accuracy is 0.5 μm or more and 5 μm
It is supplied to the following filter 49 and then transferred to the centrifugal thin film evaporative polymerization tank 41. Here, the polycondensation further proceeds while promoting the evaporation of the by-product phenol, and the intrinsic viscosity is 0.1 to
Reaches 0.5 dl / g. The centrifugal thin-film evaporative polymerization tank 41
It is operated at 180 to 300 ° C and 1 to 50 mmHg.

The polymer is further supplied to a centrifugal thin film evaporative polymerization tank 41.
It is supplied to the filter 50 having an absolute filtration accuracy of not less than 0.5 μm and not more than 5 μm through the pipe 43 by the bottom pump 56, and then transferred to the horizontal stirring polymerization tank 44 to perform final polycondensation. Since the polymer is quite viscous here, the surface is renewed by a stirring blade mounted on a horizontal rotating shaft in order to perform sufficient stirring to promote the evaporation of the by-product monomer. The horizontal stirring polymerization tank 44 has 240 to 320
It is operated at 10 ° C. or less at 10 ° C.

The polymerization product in the horizontal stirring polymerization tank 44 passes through a pipe 46 by a pump 57 and has an absolute filtration accuracy of 5 μm.
Is supplied to a filter 51 having a size exceeding 30 μm. Next, the viscous polymer is taken out from the product take-out port 52, and the intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C. is 0.20 to 1.0 dl / g, preferably 0.30 to 0.9 dl. / G, more preferably 0.3
A polycarbonate of 3-0.8 dl / g is obtained.

In the pre-polymerization tank 38, the by-produced phenol is vaporized under the polymerization tank conditions under heating and reduced pressure, and together with a part of the vaporized unreacted monomer, a distillation column (not shown) is passed through a pipe 39. Is rectified. Phenol is discharged out of the system, and unreacted monomer is returned to the polymerization tank. The prepolymerization tank 38 is evacuated by a vacuum pump (not shown) through a pipe 39.

In the centrifugal thin-film evaporative polymerization tank 41 and the horizontal stirring polymerization tank 44, by-product phenol is sucked under reduced pressure through pipes 42 and 45, respectively. Centrifugal thin film evaporative polymerization tank 41
Further, since the amount of by-product phenol generated from the horizontal stirring polymerization tank 44 is small, the distillation column is not connected to the tubes 42 and 45 as described above, and the phenol is simply condensed by the condenser.

The above reactors and reaction conditions are merely examples and are not limiting.

As described above, the polycarbonate produced by the method of the present invention is suitable not only as a general molding material but also especially as an optical lens for automobile headlamp lenses, eyeglasses, etc., and an optical recording material. Used for

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0071]

EXAMPLES In Examples and Comparative Examples, the intrinsic viscosity of a polymerization product was measured in methylene chloride at 20 ° C. using an Ubbelohde viscometer.

The hue of the produced polycarbonate (YI
Value) was measured by the following method. Cylinder temperature 290 ° C, injection pressure 1000kg / c
m, molding for 45 seconds per cycle, mold temperature 100 ° C,
The X, Y, and Z values were measured using Color an by Nippon Denshoku Industries Co., Ltd.
d Color Difference Meter
The yellowness [YI] was measured by a transmission method using ND-1001 DP. YI = 100 (1.27
7X-1.060Z) / Y The number of fine particles in the produced polycarbonate was measured by the following method. Resin was collected in a cleaning booth to which air passed through a 0.1 μm filter was pumped, and RI was collected.
Using a particle counter KL-01 manufactured by ON Company, KS-6
Using a 0 and KS-62 type sensor, 50 cc of a methylene chloride solution having a resin concentration of 10% was measured.

[0073]

Example 1 The polymerization reactor shown in FIG. 1 was used. There were two prepolymerization tanks and two horizontal stirring polymerization tanks, and one filter having absolute filtration accuracy shown below was installed at each of the stirring tank, each prepolymerization tank, and the outlet of each horizontal stirring polymerization tank.

[0074] The respective reaction conditions are as follows.

Pressure (mmHg) Temperature (° C.) Average residence time (hr) Stirring tank Nitrogen atmosphere 130 2.0 Pre-polymerization tank A 100 210 1.0 Pre-polymerization tank B 20 240 0.5 Horizontal stirring polymerization tank A 3 275 0.5 Horizontal stirring polymerization tank B 0.30 285 0.5 Bisphenol A (manufactured by Nippon GE Plastics)
0.44 mmol, 0.46 mmol of diphenyl carbonate (manufactured by Any) and 0.11 mol of tetramethylammonium hydroxide (2.5 × 10 ⁻⁴ ) as a catalyst
Mol / mol-bisphenol A) and sodium hydroxide at a ratio of 0.00044 mol (1 × 10 ⁻⁶ mol / mol-bisphenol A) are continuously supplied to a stirring tank maintained at the above temperature, and a uniform solution is obtained. Manufactured.

Subsequently, the solution was passed through a filter having the absolute filtration accuracy set at the outlet of the stirring tank, and then the pre-polymerization tank A and the pre-polymerization tank A outlet filter, followed by the pre-polymerization tank B
And a polymerization product having an intrinsic viscosity [η] of 0.18 by sequentially supplying the mixture to the outlet filter of the prepolymerization tank B. After the polymerization product was supplied to the subsequent horizontal stirring polymerization tank A and the outlet filter of the horizontal stirring polymerization tank A, the temperature was further increased to 285 ° C. and the pressure was increased to 0.
The mixture was supplied to the horizontal stirring polymerization tank B controlled at 30 mmHg to complete the polymerization, and foreign substances were removed through the final horizontal stirring polymerization tank B outlet filter. Under the above conditions, stable operation could be continued for two months. The intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank B was in the range of 0.36 ± 0.01.

No particles having a size of 10 μm or more were found in the produced aromatic polycarbonate.
The hue was YI = 0.9 ± 0.1.

The increase in the pressure difference at the outlet filter of the horizontal stirring polymerization tank B was only slightly observed two months after the start of the operation, during which time the high-quality polycarbonate as described above was replaced without replacing the filter. It could be manufactured stably.

[0079]

Example 2 An aromatic polycarbonate was produced under the same conditions as in Example 1 except that no filters were provided at the outlets of the prepolymerization tank A, the prepolymerization tank B, and the horizontal stirring polymerization tank A. The intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank B was in the range of 0.36 ± 0.01.

Further, the presence of particles of 10 μm or more was not confirmed in the produced aromatic polycarbonate.
The hue was YI = 0.9 ± 0.1.

The increase in the differential pressure of the filter at the outlet of the horizontal stirring polymerization tank B was slightly recognized two months after the start of the operation, as in Example 1. During that time, the high-quality polycarbonate as described above was filtered. It could be manufactured stably without exchanging.

[0082]

Example 3 The polymerization reactor shown in FIG. 1 was used. There are two pre-polymerization tanks and one horizontal stirring polymerization tank,
A stirring tank with a filter having the absolute filtration accuracy shown below,
One outlet was provided for each of the pre-polymerization tank and the horizontal stirring polymerization tank.

[0083] The respective reaction conditions are as follows.

Pressure (mmHg) Temperature (° C.) Average residence time (hr) Stirring tank Nitrogen atmosphere 130 2.0 Prepolymerization tank A 100 210 1.0 Prepolymerization tank B 20 240 0.5 Horizontal stirring polymerization tank 0.30 285 1.0 An aromatic polycarbonate was produced under the same conditions as in Example 1 except that the above apparatus and reaction conditions were used. Under the above conditions, stable operation could be continued for two months. The intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank was in the range of 0.36 ± 0.01.

Further, no particles having a size of 10 μm or more were found in the produced aromatic polycarbonate.
The hue was YI = 0.9 ± 0.1.

[0086]

Embodiment 4 The polymerization reactor shown in FIG. 2 was used. There are two pre-polymerization tanks, one centrifugal thin-film evaporative polymerization tank, one horizontal stirring polymerization tank, and a filter having the absolute filtration accuracy shown below in the stirring tank, each pre-polymerization tank, centrifugal thin-film evaporative polymerization tank and One was installed at each outlet of the horizontal stirring polymerization tank.

[0087] The respective reaction conditions are as follows.

Pressure (mmHg) Temperature (° C.) Average residence time (hr) Stirring tank Nitrogen atmosphere 130 2.0 Pre-polymerization tank A 100 210 1.0 Pre-polymerization tank B 20 240 0.5 Centrifugal thin-film evaporative polymerization tank 5 275 0.1 Horizontal stirring polymerization tank 0.30 285 0.5 An aromatic polycarbonate was produced under the same conditions as in Example 1 except that the above-described apparatus and reaction conditions were used. Under the above conditions, stable operation could be continued for two months. The intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank was in the range of 0.36 ± 0.01.

Further, the presence of particles of 10 μm or more was not confirmed in the produced aromatic polycarbonate.
The hue was YI = 0.9 ± 0.1.

[0090]

Comparative Example 1 An aromatic polycarbonate was produced under the same conditions as in Example 1 except that all filters were not installed. The hue of the produced aromatic polycarbonate is YI
= 1.2 ± 0.1, and the intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank B was 0.36.
The range was ± 0.01.

Further, the presence of particles of 10 μm or more was confirmed in the produced aromatic polycarbonate.

[0092]

Comparative Example 2 An aromatic polycarbonate was produced under the same conditions as in Example 1 except that a filter having an absolute filtration accuracy of 1 μm was provided only at the exit of the horizontal stirring polymerization tank B. The hue of the generated aromatic polycarbonate is YI = 0.9 ± 0.1, and the intrinsic viscosity [η] of the generated aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank B is in the range of 0.36 ± 0.01. The presence of particles of 10 μm or more was not confirmed. However, 10 days after the start of the operation, the pressure difference of the filter at the outlet of the final horizontal stirring polymerization tank B sharply increased, and it became difficult to continue the operation.

[0093]

Comparative Example 3 An aromatic polycarbonate was produced under the same conditions as in Example 3 except that all filters were not installed. The hue of the produced aromatic polycarbonate is YI
= 1.2 ± 0.1, and the intrinsic viscosity [η] of the produced aromatic polycarbonate at the outlet of the horizontal stirring polymerization tank was 0.36 ± 0.1
It was in the range of 0.01.

Further, the presence of particles of 10 μm or more was confirmed in the produced aromatic polycarbonate.

[0095]

Comparative Example 4 An aromatic polycarbonate was produced under the same conditions as in Example 4 except that all filters were not installed. The hue of the produced aromatic polycarbonate is YI =
The intrinsic viscosity [η] of the produced aromatic polycarbonate at the exit of the horizontal stirring polymerization tank was 0.36 ± 0.1.
It was in the range of 0.01.

Further, the presence of particles of 10 μm or more was confirmed in the produced aromatic polycarbonate.

As described above, the aromatic polycarbonate obtained by the method of the present invention had excellent hue and little foreign matter, and the method of the present invention was excellent in long-term operation stability.

[0098]

According to the method of the present invention, an aromatic polycarbonate having an excellent hue and containing few foreign substances can be stably obtained for a long period of time.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example of a polymerization apparatus of the method of the present invention (apparatus in which a vertical stirring polymerization tank and a horizontal stirring polymerization tank are combined).

FIG. 2 is a flow sheet showing an example of a polymerization apparatus of the method of the present invention (apparatus in which a vertical stirring polymerization tank, a centrifugal thin-film evaporation polymerization tank, and a horizontal stirring polymerization tank are combined).

[Explanation of symbols]

 1,2,6,10,14. Piping 3, 3 '. Catalyst inlet 4. Stirrer tank 5, 9, 13. Pump 7,11. 7. Vent conduit Prepolymerization tank 12. Horizontal stirring polymerization tank 15, 16, 17 Filter 18. Product outlet m ≧ 1, n ≧ 1 31. Stirring tank 32,33,34,37,40,43,46. Piping 35, 38. Prepolymerization tank 36, 36 '. Catalyst inlet 39, 42, 45. Vent conduit 41. Centrifugal thin film evaporative polymerization tank 44. Horizontal stirring polymerization tank 47, 48, 49, 50, 51. Filter 52. Product outlets 53, 54, 55, 56, 57. pump

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kimiyoshi Miura 6-12-2 Waki, Waki-machi, Kuga-gun, Yamaguchi Japan Inside GE Plastics Co., Ltd. (72) Tomoaki Shimoda Waki, Waki-machi, Kuga-gun, Yamaguchi 6-1-2, Japan GE Plastics Co., Ltd. (56) References JP-A-49-13295 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 64/00- 64/42

Claims (9)

(57) [Claims] 1. A method for producing an aromatic polycarbonate by melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester by using at least two reactors in series, and before the final reactor and at the outlet of the final reactor. Providing at least one filter in each of the methods. 2. The filter installed before the final reactor has an absolute filtration accuracy of 0.5 μm or more and 5 μm or less, and the filter at the outlet of the final reactor has an absolute filtration accuracy of more than 5 μm and 30 μm or less. The method of claim 1, wherein 3. The method according to claim 1, wherein the at least one reactor is a horizontal reactor. 4. The method according to claim 1, wherein at least three reactors are used, and at least one of the reactors is a horizontal reactor.
The method described in. 5. A (a) nitrogen-containing basic compound, and (b)
10 ^-8 to 1 based on 1 mole of the aromatic dihydroxy compound
0 ^-3 using a molar amount of a catalyst consisting of an alkali metal compound or an alkaline earth metal compound, characterized in claim 1
The method according to any one of Items 1 to 4. 6. A nitrogen-containing basic compound in an amount of 10 ^-6 to 10 ^-1 mol, and (b) an alkali metal in an amount of 10 ^-8 to 10 ^-3 mol, per 1 mol of the aromatic dihydroxy compound. 5. The method according to claim 1, wherein a catalyst comprising a compound or an alkaline earth metal compound is used. 7. A (a) nitrogen-containing basic compound, and (b)
10 ^-8 to 1 based on 1 mole of the aromatic dihydroxy compound
0 ^-3 molar amount of the alkali metal compound or an alkaline earth metal compound, and (c) The method according In any one of claims 1 to 4, characterized by using a catalyst composed of boric acid or boric acid ester. 8. A nitrogen-containing basic compound in an amount of 10 ^-6 to 10 ^-1 mol, and (b) an alkali metal in an amount of 10 ^-8 to 10 ^-3 mol, per 1 mol of the aromatic dihydroxy compound. A compound or an alkaline earth metal compound, and (c) 10 ^-8
5. A process according to claim 1, wherein a catalyst comprising 10 ^-1 molar amounts of boric acid or boric acid ester is used. 9. (a) Formula (R ¹ ) ₄ NOH (wherein each R ¹
Is independently an alkyl group having 1 to 4 carbon atoms or 6 to 10 carbon atoms.
At least one quaternary ammonium hydroxide having an aryl or aralkyl group of formula (b):
² O) ₃ B (wherein each R ² is independently a lower alkyl group or a formula X _n Ar ¹ (Ar ¹ is an aromatic hydrocarbon group having 6 to 10 carbon atoms, each X is independently an electron-withdrawing substituent, n is 0 to Ar ¹
5. The catalyst according to claim 1, wherein the catalyst comprises at least one borate ester having at least one substitutable aromatic carbon atom). Method.