JP2000143792A - Production of aromatic polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polycarbonate resin by which the stability in the degree of polymerization of the polymer can remarkably be improved. SOLUTION: An aromatic polycarbonate resin is continuously produced according to a transesterification method. In the process, a constant rate pump is installed just after one or more reactors and a differential pressure measuring instrument and a thermometer are provided on the downstream side of the constant rate pump to thereby continuously measure the degree of polymerization of the polymer on the outlet side of the reactors. The pressure of the reactors is controlled so as to keep the degree of polymerization constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an aromatic polycarbonate resin, and more particularly to a method for producing an aromatic polycarbonate resin capable of obtaining a stable polymerization degree.

[0002]

2. Description of the Related Art Polycarbonate is widely used because it has excellent mechanical properties such as impact resistance, and also has excellent heat resistance and transparency. As a method for producing such a polycarbonate, a method of directly reacting an aromatic dihydroxy compound such as bisphenol with phosgene (interfacial method) or a method of melting an aromatic dihydroxy compound such as bisphenol and an aromatic carbonate diester such as diphenyl carbonate is used. Transesterification in the state (melting method)
A method for causing this to occur is known.

Among such production methods, a method for producing a polycarbonate by a transesterification reaction between an aromatic dihydroxy compound and a carbonic acid diester does not use toxic phosgene and does not use methylene chloride as a solvent. It is a manufacturing method that does not have any problems and has attracted attention as a manufacturing method that has the possibility of being inexpensive. However, the method for continuously producing a polycarbonate by a transesterification reaction has a problem that it is difficult to stabilize the polymer quality, particularly the degree of polymerization of the polymer, as compared with the interface method.

[0004]

SUMMARY OF THE INVENTION In the present invention, there is provided a method for continuously producing a polycarbonate resin capable of obtaining a polymer quality, particularly a stable degree of polymerization, by using a transesterification method which does not have environmental problems and is excellent in economy. The purpose is to provide.

[0005]

That is, the present invention is as follows.

[0006] 1. In a method for continuously producing an aromatic polycarbonate resin by installing two or more reactors in series and reacting a mixture mainly containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst, A metering pump is installed immediately after the reactors,
By installing a differential pressure measuring device and a thermometer downstream of the metering pump, the degree of polymerization of the polymer on the outlet side of the reactor is continuously measured, and the pressure of the reactor is controlled so that the degree of polymerization becomes constant. A method for producing an aromatic polycarbonate resin.

[0007] 2. In a method of continuously producing an aromatic polycarbonate resin by installing two or more reactors in series and reacting a mixture mainly containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst, A metering pump is installed immediately after and immediately after the reactor in the last stage, and a differential pressure gauge and a thermometer are installed downstream of each metering pump to flow into and out of the final stage reactor. A method for producing an aromatic polycarbonate resin, comprising continuously measuring the degree of polymerization of a polymer to be produced, and controlling the pressure of a reactor at the final stage according to the difference in the degree of polymerization between the incoming and outgoing polymers.

The aromatic polycarbonate referred to in the present invention means that an aromatic dihydroxy compound and a carbonic acid diester, which are main components, are converted in the presence or absence of a transesterification catalyst comprising a basic nitrogen compound and an alkali metal compound.
It is an aromatic polycarbonate that has been melt-polycondensed.

As the aromatic dihydroxy compound, specifically, bis (4-hydroxyphenyl) methane, 2,2
2-bis (4-hydroxyphenyl) propane, 2,2
-Bis (4-hydroxy-3-methylphenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-
3,5-dibromophenyl) propane, bis (4-hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, p, p′-dihydroxydiphenyl, 3,3′-dichloro-4, 4 '
-Dihydroxydiphenyl, bis (hydroxyphenyl) sulfone, resorcinol, hydroquinone, 1,
4-dihydroxy-2,5-dichlorobenzene, 1,4
-Dihydroxy-3-methylbenzene, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide and the like.
Bis (4-hydroxyphenyl) propane is preferred.

Specific examples of the carbonic diester include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate. And dicyclohexyl carbonate are used, and diphenyl carbonate is particularly preferable.

Further, if necessary, the polycarbonate of the present invention may contain aliphatic diols such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and 1,10-decanediol. Examples of the dicarboxylic acids include succinic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, cyclohexanecarboxylic acid, and tereflutaic acid; oxyacids such as lactic acid, P-hydroxybenzoic acid, and 6-hydroxy-2-naphthoic acid It may contain an acid or the like.

The alkali metal compound used as the catalyst includes, for example, hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates, stearate salts of alkali metals. Borohydride, benzoate, hydrogen phosphate, bisphenol, phenol salt and the like.

Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate,
Potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium nitrate, potassium nitrate, lithium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, sodium sulfite, potassium sulfite, lithium sulfite, sodium cyanate, potassium cyanate , Lithium cyanate, sodium thiocyanate,
Potassium thiocyanate, lithium thiocyanate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, potassium borohydride, lithium borohydride, sodium phenylated borate, sodium benzoate, potassium benzoate, benzoate Examples thereof include lithium acid, 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.

The alkali metal compound as a catalyst is preferably used when the amount of the alkali metal element in the catalyst is 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per mole of the aromatic diol compound. A more desirable ratio is 5 × for the same standard.
The ratio is 10 ^-7 to 1 × 10 ^-5 equivalent.

If the amount is outside the above range, the properties of the obtained polycarbonate are adversely affected, and the transesterification reaction does not proceed sufficiently to obtain a high molecular weight polycarbonate.

As the nitrogen-containing basic compound as a catalyst, for example, tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), benzyl Ammonium hydroxides having alkyl, aryl, alkylaryl groups such as trimethylammonium hydroxide (φ-CH ₂ (Me) ₃ NOH), hexadecyltrimethylammonium hydroxide, triethylamine, tributylamine, dimethylbenzylamine, hexadecyl Tertiary amines such as dimethylamine, or tetramethylammonium borohydride (Me ₄ NB
H ₄ ), basic salts such as tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh ₄ ), and tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ). it can.

The nitrogen-containing basic compound is preferably used in such a ratio that the amount of ammonium nitrogen atoms in the nitrogen-containing basic compound is 1 × 10 ^{−5 to} 5 × 10 ⁻⁴ equivalent per mole of the aromatic diol compound. A more preferable ratio is a ratio that is 2 × 10 ^{−5 to} 5 × 10 ⁻⁴ equivalents with respect to the same standard. A particularly desirable ratio is 5 × 10 ^{−5 to} 5 × 10 ^{−4 with} respect to the same standard.
This is the equivalent ratio.

In the present invention, if desired, the alkali metal compound of the catalyst may be (a) an alkali metal salt of an ate complex of an element of Group 14 of the periodic table or (b) an oxo acid of an element of Group 14 of the periodic table. Can be used. Here, the elements of Group 14 of the periodic table refer to silicon, germanium, and tin.

The use of these alkali metal compounds as a polycondensation reaction catalyst has the advantage that the polycondensation reaction can be promptly and sufficiently promoted. Further, undesirable side reactions such as a branching reaction generated during the polycondensation reaction can be suppressed to a low level.

(A) As an alkali metal salt of an ate complex of an element of group 14 of the periodic table, those described in JP-A-7-268091 are mentioned. Specifically, a compound of germanium (Ge); NaGe (OMe) ₅ , NaGe
(OEt) ₃ , NaGe (OPr) ₅ , NaGe (OB
u) ₅ , NaGe (OPh) ₅ , LiGe (OMe) ₅ ,
LiGe (OBu) ₅ and LiGe (OPh) ₅ can be given.

As a compound of tin (Sn), NaSn
(OMe) ₃ , NaSn (OMe) ₂ (OEt), NaS
n (OPr) ₃ , NaSn (On-C ₆ H ₁₃ ) ₃ , Na
Sn (OMe) ₅ , NaSn (OEt) ₅ , NaSn (O
_{Bu) 5, NaSn (O-} n-C 12 H 25) 5, NaSn
(OEt), NaSn (OPh) ₅ , NaSnBu ₂ (O
Me) ₃ can be mentioned.

(B) Examples of the alkali metal salt of oxo acid of Group 14 element of the periodic table include silicic acid (silicic acid).
Cic acid), stannic acid (sta)
alkali metal salt of germanic acid, germanium (II) acid, germanic acid (germanic acid), germanic acid (germanic acid)
The alkali metal salts of acid) can be mentioned as preferred.

The alkali metal salt of silicic acid is, for example, an acidic or neutral alkali metal salt of monosilicic acid (monosilicic acid) or a condensate thereof, and examples thereof include monosodium orthosilicate, disodium orthosilicate, and orthosilicate. Trisodium and tetrasodium orthosilicate can be mentioned.

The alkali metal salt of stannic acid is, for example, an acidic or neutral alkali metal salt of monostannic acid or a condensate thereof, and examples thereof include disodium monostannate (Na ₂ SnO ₃ .C).
_{H 2 O, x = 0~5)} , mention may be made of Monosuzu acid tetrasodium salt (Na ₄ SnO _4).

Germanium (II) acid (germano)
The alkali metal salt of us acid) is, for example, an acidic or neutral alkali metal salt of monogermanic acid or a condensate thereof, and examples thereof include monosodium germanate (NaHGeO ₂ ).

Germanium (IV) acid (germani)
The alkali metal salt of c acid) is, for example, an acidic or neutral alkali metal salt of monogermanic acid (IV) acid or a condensate thereof, for example, monolithium orthogermanate (LiH ₃ GeO ₄ ) orthogermanic acid Disodium salt, tetrasodium orthogermanate, disodium digermanate (Na
₂ Ge ₂ O ₅ ), disodium tetragermanate (Na ₂ Ge ₄ O ₉ ), and disodium pentagermanate (Na ₂ Ge ₅ O ₁₁ ).

In the above polycondensation reaction catalyst, the alkali metal element in the catalyst is 1 × per mole of the aromatic diol compound.
It is preferably used in the case where it becomes 10 ^{-8 to} 5 × 10 ^-5 equivalent. A more desirable ratio is 5 × 10 ⁻⁷ to 1 with respect to the same standard.
× 10 ⁻⁵ equivalent.

In the polycondensation reaction of the present invention, at least one cocatalyst selected from the group consisting of an oxo acid of Group 14 element of the periodic table and an oxide of the same element is optionally used together with the above catalyst. Can coexist.

By using these cocatalysts in a specific ratio, the terminal block reaction and the polycondensation reaction rate are not impaired, the branching reaction which is easily generated during the polycondensation reaction, and the foreign matter in the apparatus at the time of molding are performed. Undesirable side reactions such as generation and burning can be more effectively suppressed.

The oxo acids of Group 14 elements of the periodic table include, for example, silicic acid, stannic acid and germanic acid.

The oxides of Group 14 elements of the periodic table include:
Mention may be made of silicon monoxide, silicon dioxide, tin monoxide, tin dioxide, germanium monoxide, germanium dioxide and condensates thereof.

The co-catalyst should be present in a proportion such that the metal element of Group 14 of the periodic table in the co-catalyst is 50 moles (atoms) or less per mole (atom) of the alkali metal element in the polycondensation reaction catalyst. preferable. If the co-catalyst is used in a proportion of more than 50 moles (atoms) of the same metal element, the rate of the polycondensation reaction is undesirably reduced.

The cocatalyst is present in such a proportion that the metal element of Group 14 of the periodic table of the cocatalyst is 0.1 to 30 mol (atoms) per 1 mol (atom) of the alkali metal element of the polycondensation reaction catalyst. Is more preferred.

These catalyst systems have an advantage that the polycondensation reaction and the terminal blocking reaction can be promptly and sufficiently proceeded by being used in the polycondensation reaction. Further, undesirable side reactions such as a branching reaction generated in the polycondensation reaction system can be suppressed to a low level.

The polymerization degree control of the present invention comprises accurate on-line detection of the degree of polymerization and a method of controlling the polymerization reaction based on the data of the degree of polymerization.

As a method for simply detecting the degree of polymerization of a desired polymer in the polymerization of polycarbonate, it is generally practiced to measure the melt viscosity of the polymer. Such a viscosity measurement method includes a method of measuring a torque of a rotating body in a melt and a power required for rotating the melt, and a method of flowing a melt in a pipe and requiring energy and pressure loss required at that time. Is roughly divided into two methods.

Among them, the former is carried out by detecting the stirring power of the reactor or by introducing the polymer to a dedicated measuring section. However, the method of measuring the stirring power has a large error and allows precise polymerization degree control. There is a problem that the method using a dedicated measurement unit is not suitable for online detection. The latter is a method suitable for on-line detection, but has a problem in its measurement accuracy when used for precise control of the degree of polymerization.

The inventors of the present application measured the polymer viscosity accurately by measuring the differential pressure of the molten polymer flowing in the pipe, and searched for a method for online measurement of the degree of polymerization based on the viscosity. By controlling the flow rate, temperature, and flow state of the polymer constantly, we succeeded in obtaining accurate differential pressure data that can be used for controlling the degree of polymerization online.

The metering pump used in the present invention is not particularly limited and may be any combination of various general metering pumps. Examples thereof include a gear pump, a plunger pump, a diaphragm pump, and a rotary pump. Momentary fluctuations in the flow rate should be avoided as much as possible, and in the case of a gear pump, it is preferable that the operating speed be 5 rpm or more. When a plunger pump or a diaphragm pump is used, it is preferable to use multiple pumps whose phases are shifted so as to eliminate pulsation.

In the present invention, it is important that the temperature of the polymer flowing in the pipe be strictly measured by the differential pressure measuring section. For this reason, in the present invention, it is preferable to install a thermometer immediately before, immediately after, or between two or more pressure gauges for measuring a differential pressure.

In the present invention, the surface roughness of the inner surface of the pipe for measuring the differential pressure is important, and it is important to finish the pipe smoothly at Rmax of 1.6 S or less. When the aperture is stopped down, it is preferable to stop down smoothly so that the apex angle of the aperture is 20 ° or less.

In the present invention, a differential pressure measuring device according to the method of the present invention described above is installed at the outlet side of the final reactor, the degree of polymerization is detected online, and the polymerization conditions are controlled based on this to keep the degree of polymerization constant. Although it is possible to control the polymerization degree of the polymer flowing into the final reactor from the differential pressure according to the method of the present invention, it is strictly necessary to control the polymerization conditions based on the polymerization degree difference from the exit polymer. It is more preferable to control the degree of polymerization. Further, by controlling the degree of polymerization in the reactor upstream of the last stage in the same manner as in the last stage, even better control of the degree of polymerization can be carried out, but this should be considered as falling within the scope of the present invention.

In the present invention, the degree of polymerization is controlled by controlling the reaction pressure based on the degree of polymerization data detected online as described above.

In general, in the transesterification method, the polymerization rate can be controlled also by the polymer temperature or the number of rotations of the stirring. However, when the temperature of the polymer is changed, this method involves changing the temperature of the jacket heating medium of the reactor. In the case of adopting the method, since it takes a considerable time from the change of the conditions to the influence on the polymerization rate to be controlled, it is very difficult to control the polymerization rate by the polymer temperature.

Further, when the polymerization rate is controlled by the rotation speed of the reactor under stirring, heat is generated by stirring heat, and it is necessary to remove the heat generated by changing the temperature of the jacket heating medium. It is very difficult to control the polymerization rate by the number of rotations for stirring because of the delay.

According to the study by the inventors of the present invention, when the polymerization rate is controlled by the pressure in the reactor, there is no influence on others, and the time delay of the influence of the pressure change on the polymerization rate is also reduced. It was found to be very short and optimal as a control factor.

As a method of controlling the pressure in the reactor, for example, a method in which the pressure in the reactor or the pressure in the vapor pipe is detected to adjust the opening of a valve for entering a vacuum source, or a method in which air is blown immediately before the vacuum source is used. A method of adjusting the amount of the active gas can be considered, and any arbitrary pressure control method can be used in the present invention without any particular limitation.

The vacuum source used in the present invention is not particularly limited, and any vacuum source that can be generally used can be used alone or in any combination. Typical examples include an oil rotary vacuum pump, a roots vacuum pump, a liquid ring vacuum pump, and an ejector.

In the present invention, there are no particular restrictions on the equipment and process used to produce a polycarbonate by transesterifying a mixture mainly containing an aromatic dihydroxy compound and a carbonic acid diester, and there are no particular restrictions on a conventionally known continuous polymerization equipment or a continuous polymerization equipment. A process can be used, for example the following:

That is, devices having respective functions such as raw material preparation, raw material supply, initial polymerization, and late polymerization are arranged in series,
In addition, for the preparation and supply of the catalyst, it is common to use equipment that is in a different system from those described above and that can be continuously supplied to the polymerization reaction tank as needed.

The apparatus capable of performing the polymerization reaction is as follows:
In many cases, this is carried out by arranging two or more reaction vessels in series. On the other hand, there is a technique in which a reaction vessel in the middle is branched to continuously obtain polycarbonates having different degrees of polymerization. Therefore, in the following, for convenience of explanation, the polymerization reaction is divided into an initial polymerization reaction and a late polymerization reaction,
The description will be made on the assumption that two reaction tanks, an initial polymerization reaction tank for promoting the initial polymerization reaction and a late polymerization reaction tank for promoting the late polymerization reaction, are arranged in series.

The term "initial polymerization reaction" used herein refers to the initial reaction region of the transesterification reaction, that is, the degree of polymerization and the viscosity of the polymer produced as a result of the reaction are low, and the unreacted aromatic dihydroxy compound or carbonate diester is used. It means a region where the diffusion resistance in liquid is negligible when considering the removal of a monohydroxy compound by-produced outside the reaction system as a relatively large amount.

More specifically, the viscosity average molecular weight is 100
It often refers to a region from 0 to 10000, preferably from 2000 to 8000. "Initial polymerization reaction tank" means a reaction tank for allowing this initial polymerization reaction to proceed, and may also mean a group of reaction tanks composed of one or more reaction tanks.

The term "late-stage polymerization reaction" refers to the late-stage region of the transesterification reaction, that is, the degree of polymerization and the viscosity of the polymer produced as a result of the transesterification reaction are high, and the terminal OH group involved in the transesterification reaction. And a relatively small number of phenyl groups, which means that the diffusion resistance in liquid cannot be ignored in considering removal of a monohydroxy compound by-produced outside the reaction system.

More specifically, the viscosity average molecular weight is 100
After the initial polymerization reaction, which is a region from 0 to 10000, preferably from 2000 to 8000, it often refers to a region from the production of polycarbonate as a product. "Late polymerization reaction tank" means a reaction tank for allowing this late polymerization reaction to proceed, and may also mean a group of reaction tanks comprising one or more reaction tanks. Note that this division is only for convenience and may be further divided.

In the continuous operation, there are cases where the preparation of the raw materials is dissolved in a batch system and cases in which the raw materials are continuously prepared.

In the case of batchwise operation, a fixed amount of molten carbonic acid diester is charged into a raw material preparation tank, and then the molar ratio of carbonic acid diester to aromatic dihydroxy compound is usually 0.8 to 1.5, preferably 0 to 1.5. After the aromatic dihydroxy compound is gradually charged and uniformly melted with stirring so as to be 0.95 to 1.10, more preferably 1.00 to 1.05, the mixture is maintained at a constant temperature and transferred to the raw material supply tank. In this case, the temperature depends on the melting point of the raw material,
It is often 0 to 180 ° C.

In the case of continuously preparing and dissolving the raw materials, the molten carbonic acid diester and the molten aromatic dihydroxy compound are continuously supplied at a constant ratio to a preparation tank equipped with a stirrer. That is common. In this case, the raw material preparation tank and the raw material supply tank can be combined. Further, when the molten carbonic acid diester and the molten aromatic dihydroxy compound are mixed in a pipe equipped with a line mixer, the raw material preparation tank or both the raw material preparation tank and the raw material supply tank can be omitted. . In these cases, it is necessary to maintain the temperature above the melting point of each raw material and mixture, and usually 100 to 180 ° C is used.

Regardless of batch type or continuous type, in the operation of dissolving and preparing the raw materials, the presence of air, particularly oxygen, should be avoided, and the apparatus used for dissolving and preparing should be sufficiently replaced with an inert gas such as nitrogen. It is preferable to perform purging with an inert gas. In many cases, it is also effective to replace an atmosphere in contact with an aromatic dihydroxy compound or a carbonic acid diester before charging with an inert gas in advance.

The raw material thus prepared is supplied to the initial polymerization tank while being controlled to a substantially constant amount via a metering pump as required. As the metering pump to be used, generally, the viscosity of the molten raw material and its mixture is low,
For example, a plunger pump, a diaphragm pump, which can secure a sufficient discharge pressure, is excellent in quantitativeness, and a type of pump suitable for low-viscosity liquid is used, and there is a case where a back pressure valve is installed on the discharge side. Many.

The fine foreign matter present in the raw material in the process of supplying the raw material prepared by dissolution to the initial polymerization tank is removed by performing filtration at an arbitrary stage during the supply from the dissolution preparation to the initial polymerization reaction tank. be able to. As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used, and the filter having an opening of 10 μ or less, preferably 5 μ or less is used.

When a transesterification catalyst is used, a group of equipment having a system similar to that of the raw material preparation tank is used, and a separate line from the raw material supply line in the initial reactor or in the middle thereof at a fixed ratio to the raw material supply amount. Supplied. Transesterification catalysts are often used in the form of a solution or dispersion in a solvent, but in this case, they affect the reaction of water, monohydroxy compounds such as phenol, aromatic dihydroxy compounds used as raw materials, or carbonic acid diester. Is preferably used as a solvent.

As the initial polymerization reaction tank, a cascade tank in which a horizontal reaction tank with or without a stirrer is partitioned by a partition plate can be used, but a baffle is provided with or without a stirrer. It is possible to employ a vertical complete mixing tank with or without. Of these, it is most common to employ a vertical complete mixing tank provided with a stirrer and without a baffle inside.

In this case, the initial polymerization reaction tank is provided with an internal coil and an external heat exchanger in order to secure a large heat transfer area, and is used to separate the monohydroxy compound generated in the reaction from the carbonic acid diester as a raw material. A rectification column equipped with a reflux mechanism is preferably used. When there are a plurality of vertical stirring tanks having the same operation pressure, a rectification column having one reflux mechanism can be shared.

When a plurality of reaction tanks are used as the initial polymerization reaction tank, it is important to keep the residence time of each reaction tank constant in order to suppress variations in the color tone and degree of polymerization of the product polycarbonate. . For this reason, liquid level control using a head (static pressure of the reaction mixture), liquid level control by arranging a control valve in the transfer pipe and interlocking with the level meter of the reaction tank, and quantitative measurement such as a gear pump in the transfer pipe A liquid sending pump is provided and the liquid level is controlled in conjunction with the level meter of the reaction tank, and the residence time of each reaction tank is usually 5 hours or less, preferably 2 hours or less. , More preferably for 1 hour or less.

The operating conditions for the initial polymerization reactor are 180 to 25.
Although a temperature of 0 ° C. and a pressure of 100 to 10 hPa are often used, a large amount of an inert gas may be circulated in this state or at normal pressure or under pressure in place of reduced pressure. In general, the operating temperature and the degree of vacuum are generally strengthened in the subsequent stirring tank as the transesterification progresses (the operating temperature is increased and the numerical value of the degree of vacuum is reduced).

Thus, in the initial polymerization reactor, the viscosity average molecular weight is 1,000 to 10,000, preferably 2,000 to 10,000.
Polymerization is performed up to 8000, and the reaction rate of the raw material is 95% or more, preferably 99% or more, and more preferably 99.5%.
It is common practice to increase to the above.

The reactant generated in the initial polymerization reaction tank is quantitatively supplied to the latter polymerization reaction tank using a gear pump or the like. During this process and during the initial polymerization, the reaction product may be filtered for the purpose of removing foreign substances, if necessary. As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used, and the filter having an opening of 20 μm or less, preferably 10 μm or less is used.

The late-stage polymerization reactor is a horizontal reactor equipped with a stirrer having one or more stirring shafts in the horizontal direction, and a cross section of the reactor having a circular or nearly circular shape or a combination of eyeglasses or the like is used. It is possible to adopt a shape in which a partition plate is installed as required therein. When a partition plate is provided, the partition plate may be attached to the reaction tank itself, but is often attached to a stirrer.

Since the latter polymerization reactor is operated at a high degree of vacuum, it is rare to have a rectification column, and low molecular weight compounds such as a monohydroxy compound are generated by a route directly connecting the latter polymerization reactor to the vacuum generator. Is often removed by a collector during the process.

As the stirrer used in the latter stage polymerization reaction tank, there are a stirrer having a single shaft (single shaft stirrer) and a two-shaft stirrer (double shaft stirrer). Machine
The viscosity of the reactants under operating conditions is 8000 poise or less, preferably 6000 poise or less, more preferably 40 poise or less.
In most cases, a twin-screw stirrer is used at a viscosity higher than 00 poise.

As the stirring blade used for stirring, various shapes of stirring blades are used in order to increase the surface area of the reaction mixture and to reduce the staying portion. For example, a spectacle-shaped or lattice-shaped stirring blade attached vertically to the stirring shaft, an eccentric disk placed vertically to the stirring shaft while shifting the phase, a lens-shaped paddle to the stirring shaft while shifting the phase There is a vertical installation, a paddle with a scraper at the tip installed vertically to the stirring shaft, etc., and from the shell to engage with these blades for the purpose of reducing dead space in the tank and around the stirring blades. Examples include a stator installed or a plurality of blades arranged so as to face each other and mesh with each other. When a plurality of blades are used, the rotation direction and the speed may be the same or different.

If the viscosity of the reactant exceeds 5,000 poise, the reactant may adhere to the extraction pipe and may not be smoothly supplied to the extraction pump, and the residence time may fluctuate. For the purpose of avoiding such a problem, a reaction tank provided with a single-screw or twin-screw for extracting a reactant from the late-stage polymerization reaction tank is preferably used.

When a plurality of late-stage polymerization reactors are connected in series, it is important to maintain a constant residence time in each reactor in order to keep physical properties such as the degree of polymerization and color tone of the polycarbonate product constant. Yes, for example, a liquid pump such as a gear pump is provided in the transfer pipe, and liquid level management is performed by linking the liquid transfer amount with the level meter of the reaction tank before or after the liquid transfer pump. You.

Usually, the residence time of each reaction tank is maintained at 10 hours or less, preferably 5 hours or less, more preferably 2 hours or less.

The operating conditions for the late polymerization reactor are 250 to 32.
A temperature of 0 ° C. and a pressure of 10 to 0.1 hPa are often used. It is general that the operating temperature and the degree of vacuum are sequentially strengthened in the subsequent stirring tank (the temperature is made higher and the value of the degree of vacuum is made smaller). In this way, polymerization is generally carried out in the late reaction tank up to a viscosity average molecular weight of 10,000 or more, preferably 15,000 or more, depending on the purpose.

The reaction product produced in the late polymerization reactor is quantitatively extracted using a gear pump or the like, and if necessary, additives are added. Then, the reaction product is produced in the form of pellets, thin films, molded products, and the like. If necessary, the reaction product is filtered for the purpose of removing foreign substances. As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used. The aperture is 40 μ or less when the viscosity average molecular weight of the product is 20,000 or less, and 100 μ or less when the viscosity average molecular weight is more than 20,000. Are commonly used.

Regarding the materials of the equipment parts used for the production of polycarbonate, the raw material preparation tank, the raw material supply tank, the catalyst preparation tank, the catalyst supply tank, the reaction tank, and the associated piping,
Parts where valves, agitators, etc. come into contact with the reaction mixture (liquid contact part)
And the material of the material used for the part where the scattered matter and the evaporant come into contact with each other is preferably a material with little iron, such as nickel,
Substances that do not easily react with acids or basic substances, such as stainless steel, are preferably used. The reason is that it is desirable to have corrosion resistance to the monohydroxy compound generated in the early stage of the transesterification reaction. Further, although the cause is unknown, these metals color the produced polycarbonate or promote the crosslinking reaction to promote gelation. This is because the quality may be degraded by increasing the number of times.

A catalyst deactivator can be added to the polycarbonate obtained in the present invention. As the catalyst deactivator used in the present invention, known catalyst deactivators are effectively used. Among them, ammonium salts of sulfonic acids and phosphonium salts are preferable, and furthermore, tetrabutylphosphonium salts of dodecylbenzenesulfonic acid and the like are preferable. The above salts of dodecylbenzenesulfonic acid and the above salts of paratoluenesulfonic acid such as tetrabutylammonium paratoluenesulfonate are preferred. As sulfonic acid esters, methyl benzenesulfonate, ethyl benzenesulfonate, butylbenzenesulfonate, octylbenzenesulfonate, phenylbenzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butylparatoluenesulfonate, para Octyl toluenesulfonate, phenyl paratoluenesulfonate and the like are preferably used, and among them, tetrabutylphosphonium dodecylbenzenesulfonate is most preferably used.

The amount of the catalyst deactivator used is 0.5 to 50 mol, preferably 0.5 to 50 mol, per 1 mol of the polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds. It can be used at a ratio of 10 mol, more preferably at a ratio of 0.8 to 5 mol.

These catalyst deactivators are added directly to a molten polycarbonate and kneaded, or dissolved or dispersed in an appropriate solvent. There is no particular limitation on the equipment used to carry out such an operation, but for example, a twin-screw ruder is preferable, and a vented twin-screw ruder is particularly preferable when the catalyst deactivator is dissolved or dispersed in a solvent. used.

In the present invention, additives can be added to the polycarbonate within a range that does not impair the object of the present invention. This additive is preferably added to the molten polycarbonate similarly to the catalyst deactivator. Examples of such an additive include a heat stabilizer, an epoxy compound, an ultraviolet absorber, a release agent, a colorant, Slip agents, anti-blocking agents, lubricants, organic fillers, inorganic fillers and the like can be mentioned.

Of these, heat stabilizers, ultraviolet absorbers, release agents, coloring agents and the like are particularly generally used, and two or more of these can be used in combination.

Examples of the heat stabilizer used in the present invention include a phosphorus compound, a phenol stabilizer, an organic thioether stabilizer, a hindered amine stabilizer and the like.

As the ultraviolet absorber, a general ultraviolet absorber is used, for example, a salicylic acid ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a cyanoacrylate ultraviolet absorber and the like. Can be mentioned.

As the release agent, generally known release agents can be used, for example, hydrocarbon release agents such as paraffins, fatty acid release agents such as stearic acid, and stearamide. Release agents such as fatty acid amides, alcohol release agents such as stearyl alcohol and pentaerythritol, fatty acid ester release agents such as glycerin monostearate and pentaerythritol stearate, and silicone release agents such as silicone oil. And the like.

As the colorant, an organic or inorganic pigment or dye can be used.

The method of adding these additives is not particularly limited. For example, they may be directly added to polycarbonate, or master pellets may be prepared and added.

[0089]

According to the present invention, two or more reactors are installed in series to react an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst, thereby continuously producing an aromatic polycarbonate resin. In the manufacturing method,
A metering pump is installed immediately after one or more reactors, and a differential pressure gauge and a thermometer are installed downstream of the metering pump to continuously measure the degree of polymerization of the polymer on the outlet side of the reactor. By controlling the pressure of the reactor so that the degree of polymerization becomes constant, a method for producing a polycarbonate resin which can significantly improve the stability of the degree of polymerization of the polymer can be provided.

[0090]

The present invention will be described below with reference to examples and comparative examples. This embodiment is intended to exemplify the present invention, and the present invention is not limited by the embodiment. For the measurement of the viscosity average molecular weight in the examples and comparative examples, 0.1 was used.
The intrinsic viscosity of a 7 g / dl methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following equation. [Η] = 1.23 × 10 ⁻⁴ × M ^0.83

Example 1 Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.01 mol to 1 mol of 2,2-bis (4-hydroxyphenyl) propane, and nitrogen was added thereto. After the replacement, the mixture was heated and dissolved, and the molten mixture was transferred to a raw material storage tank. The processes related to the reaction after the raw material storage tank were continuously operated.

The details of the embodiment will be described below. The raw material storage tank is continuously fed to the first-stage vertical reactor using a metering pump, and 1 × 10 ⁻⁶ equivalent of sodium phenoxide is added to 1 mol of 2,2-bis (4-hydroxyphenyl) propane. And 1 × 10 ⁻⁴ equivalents of tetramethylammonium hydroxide were also continuously added to the reactor.

Phenol produced and vaporized in the first vertical reactor and partially vaporized raw material (2,2-bis (4-
(Hydroxyphenyl) propane and diphenyl carbonate) were continuously rectified in a rectification column attached to the reactor, and then transesterification proceeded continuously while only phenol was distilled out of the reaction system. .

In the first stage vertical reactor, the prepolymer temperature was 220 ° C. and the reactor pressure was 13333 Pa (100 m
mHg).

The prepolymer produced in the first-stage vertical reactor was continuously withdrawn from the bottom of the tank using a gear pump, and was continuously fed to the second-stage vertical reactor. The prepolymer was withdrawn from a valve provided on the outlet side of the gear pump, and the viscosity average molecular weight was measured.

The prepolymer was further continuously fed to a second vertical reactor, and phenol produced and vaporized in the reactor and the remaining raw material (2,2-bis (4-hydroxyphenyl) partially vaporized ) Propane and diphenyl carbonate) were continuously rectified in a rectification column attached to the reactor, and then the ester exchange reaction was continuously advanced while only phenol was distilled out of the reaction system.

In the second stage reactor, the prepolymer temperature was 250 ° C. and the reactor pressure was 2000 Pa (15 mmHg).
The polymerization was carried out.

The prepolymer obtained in the second stage reactor was continuously withdrawn using a gear pump, and was continuously fed to the final stage polycondensation reactor. The prepolymer was withdrawn from a valve installed on the outlet side of the gear pump, and the viscosity average molecular weight was measured to be 6,000.

The polycondensation reaction was allowed to proceed continuously while all the phenol and the like generated and vaporized in the horizontal reactor at the final stage where the prepolymer was fed was distilled out of the reaction system.

In the final polycondensation reactor, polymerization was carried out at a polymer temperature of 270 ° C. and a reactor pressure of about 133 Pa (1 mmHg).

The polymer obtained in the polycondensation reactor at the final stage is continuously and quantitatively extracted using a gear pump, and at the same time, continuously sensed by a differential pressure measuring instrument and a temperature detecting terminal installed after the gear pump. Pressure and polymer temperature were measured so that the molecular weight of the polymer could be calculated continuously.

When the pressure in the final polymerization tank was controlled according to the difference between the molecular weight calculated continuously and the target value, the viscosity average molecular weight of the obtained pellets was 15500 ± 200.
In the range.

Example 2 The procedure in Example 2 was repeated up to the reaction in the second-stage reactor. The prepolymer obtained in the second-stage reactor is continuously extracted using a gear pump, and at the same time, the differential pressure and the polymer temperature are continuously measured by a differential pressure measuring device and a temperature detecting terminal installed after the gear pump. The molecular weight of the polymer was continuously calculated, and was continuously fed to the final stage polycondensation reactor. The prepolymer was withdrawn from a valve installed on the outlet side of the gear pump and the viscosity average molecular weight was measured.

The prepolymer was continuously supplied to the horizontal reactor at the final stage, and the polycondensation reaction was further advanced.

In the final polycondensation reactor, polymerization was carried out at a polymer temperature of 270 ° C. and a reactor pressure of about 133 Pa (1 mmHg).

The polymer obtained in the polycondensation reactor at the final stage is continuously and quantitatively extracted using a gear pump, and the differential pressure is continuously measured by a differential pressure gauge installed after the gear pump. The molecular weight of the polymer could be calculated continuously.

Further, when the pressure of the final polymerization tank was controlled in accordance with the molecular weight difference between the reactor and the reactor calculated continuously,
The viscosity average molecular weight of the obtained pellet is 15500 ± 10
0 was maintained in the range.

[Comparative Example 1] The pressure of the final polymerization tank was 133 P
The same procedure as in Example 2 was carried out except that the temperature was constant at a (1 mmHg). As a result, the viscosity average molecular weight of the pellets obtained on the outlet side of the polymerization tank varied greatly to 15500 ± 500.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Sawaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Co., Ltd. Inside the Iwakuni Research Center (72) Inventor Katsushi Sasaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Shares F term in the Iwakuni Research Center (reference) 4J029 AA10 AB04 AC01 AD01 BB04A BB05A BB05B BB10A BB12A BB13A BB13B BF14A BG05X BG07X BG08X BG21 BH02 DB07 DB11 HA01 HC04A HC05A HC05B JA091J01 J03 J011J03 JF361 JF371 KD05 KE02 KE07 KJ05 LB09

Claims (2)

[Claims] 1. An aromatic polycarbonate resin is continuously produced by installing two or more reactors in series and reacting a mixture mainly containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In this method, a metering pump is installed immediately after one or more reactors, and a differential pressure measuring device and a thermometer are installed downstream of the metering pump to continuously control the degree of polymerization of the polymer at the outlet side of the reactor. A method for producing an aromatic polycarbonate resin, comprising measuring and controlling the pressure of a reactor so that the degree of polymerization is constant. 2. An aromatic polycarbonate resin is continuously produced by installing two or more reactors in series and reacting a mixture mainly containing an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In the method, a metering pump is installed immediately after the reactor at the last stage and immediately after the reactor immediately before the last stage, and a differential pressure measuring device and a thermometer are installed downstream of each metering pump, whereby the reaction at the final stage is performed. A method for producing an aromatic polycarbonate resin, comprising continuously measuring the degree of polymerization of a polymer flowing into and out of a reactor, and controlling the pressure in a final stage reactor in accordance with the difference in the degree of polymerization of the incoming and outgoing polymers.