JP2002080577A - Method and apparatus for manufacturing polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polycarbonate resin capable of largely improving the stability of molecular weight of the polymer. SOLUTION: A method for continuously manufacturing a polycarbonate through an ester interchange reaction by placing two or more reactors in series. In the method, the molecular weight of the polymer at the discharging side of a reactor is continuously measured by placing a metering pump directly behind one or more reactors, and further placing a pressure difference meter and a thermometer on the downstream side of the metering pump. The deviation and the speed of changing to be held are measured at an interval of 1 to 120 min, a PID action controller is actuated according to the measurements to control vacuum automatically, and the vacuum-keeping operation is repeated at an interval of 1 to 120 min so that the molecular weight is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polycarbonate, and more particularly to a method for producing a polycarbonate capable of obtaining a stable polymer molecular weight.

[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 polymer molecular weight, as compared with the interface method.

[0004]

SUMMARY OF THE INVENTION In the present invention, a polycarbonate resin which can obtain a polymer quality, particularly a stable polymerization degree (in other words, a molecular weight) by using a transesterification method which does not have environmental problems and is excellent in economical efficiency. The purpose of the present invention is to provide a continuous production method.

[0005]

That is, the present invention comprises the following technology.

[0006] 1. A method for producing a polycarbonate by a melt polymerization method, including automatically controlling a degree of vacuum D inside a reactor according to a measured value A of a polymer molecular weight at a reactor outlet, at a time interval of 1 to 120 minutes, The deviation, the amount and the rate of change between the measured molecular weight A and the molecular weight C to be maintained are measured, and the degree of vacuum D is automatically controlled by the PID operation controller in accordance with the measured value. A method for producing a polycarbonate for controlling the molecular weight.

[0007] 2. A method for producing a polycarbonate by a melt polymerization method, comprising automatically controlling a degree of vacuum D inside a reactor according to a difference between a measured value A of polymer molecular weight at a reactor outlet and a measured value B of polymer molecular weight at an inlet of the reactor. At a time interval in the range of 1 to 120 minutes, the deviation, the amount of change, and the rate of change between the measured molecular weight A and the measured measured molecular weight B of the polymer are measured, and the PID operation controller adjusts the vacuum accordingly. A method for producing a polycarbonate wherein the polymer molecular weight at the reactor outlet is controlled by automatically controlling the degree C.

[0008] 3. The reactor is provided with a metering pump at an outlet or an inlet and an outlet thereof, and a differential pressure measuring device and a thermometer are installed downstream of the metering pump, thereby obtaining a measured value of polymer molecular weight. 3. The method for producing a polycarbonate according to 1 or 2.

4. A reactor, a metering pump installed at an outlet or an inlet and an outlet thereof, a molecular weight measuring unit including a differential pressure measuring device and a thermometer installed downstream of the metering pump, and a vacuum inside the reactor. Degree measuring means, 1 to 12
At time intervals in the range of 0 minutes, the measured molecular weight A at the reactor outlet is
And control means for automatically controlling the degree of vacuum D by adjusting the PID operation in accordance with the deviation, the amount of change and the rate of change between the molecular weight C to be maintained or the measured molecular weight B at the inlet of the reactor. Polycarbonate production equipment including.

In the present invention, for example, an aromatic dihydroxy compound and a carbonic acid diester are reacted in the presence / absence of a catalyst by installing two or more reactors in series to produce polycarbonate continuously. , 1
A metering pump is installed immediately after the number of reactors, and a differential pressure measuring device and a thermometer are installed downstream of the metering pump to continuously measure the polymer molecular weight on the outlet side of the reactor. The molecular weight of the polymer flowing out of the reactor can be kept constant by automatically controlling the pressure (degree of vacuum) of the reactor accordingly.

In the present invention, the metering pump, the differential pressure measuring device and the thermometer are preferably installed at the outlet of the reactor whose molecular weight is to be controlled and the reactor immediately before the reactor.
Thereby, the molecular weight of the polymer flowing into and out of the reactor is continuously measured, and the pressure of the reactor for controlling the molecular weight according to the difference in the molecular weight of the polymer entering and exiting the reactor is controlled. It is possible to keep the molecular weight of the polymer flowing out of the membrane constant.

The metering pump used in the present invention is not particularly limited, and can be any combination of various general metering pumps. Examples thereof include a gear pump, a plunger pump, and a rotary pump.

The differential pressure measuring device measures the flow resistance of the polymer in the pipe, that is, the pressure loss, and can calculate the viscosity of the polymer from the pressure loss. Further, the molecular weight of the polymer can be calculated by measuring the temperature of the polymer in the pipe using the polymer viscosity obtained above and the thermometer. By controlling the pressure of the reactor according to the difference between the measured value of the molecular weight and the target value, the polymer molecular weight at the outlet of the reactor can be made constant.

In the conventional method, the pressure loss is measured,
A method of controlling the molecular weight by determining the viscosity of the polymer from this, calculating the molecular weight in consideration of the influence of temperature, and controlling the pressure of the reactor so that the molecular weight reaches the target molecular weight is known. Was. However, if the molecular weight is actually controlled based on this method, the fluctuation range of the molecular weight becomes large, the stability of the control becomes insufficient, and often a manual stabilization is required. It was missing. The present inventors have conducted intensive studies in order to solve these problems, and as a result, have found the following important findings.

That is, when controlling the molecular weight by the pressure in the reactor, there is a delay time (about 1 to 120 minutes) from when the pressure is changed to when the molecular weight is affected. Without considering the effect of the delay time, if a further pressure change is applied while the previously performed pressure change is affecting the molecular weight, the molecular weight will diverge and a stable molecular weight control cannot be performed. Therefore, the point of the present invention lies in the establishment of a method for controlling the molecular weight in consideration of the time from when the pressure is changed until the molecular weight is affected, that is, the so-called delay time.

According to the study by the inventors of the present invention, it has been found that the delay time is about 1 to 120 minutes although it depends on the type of equipment used. Based on the results of these studies, the inventors of the present invention have established the following automatic control method of molecular weight which is much more excellent in controllability than the conventional control method.

That is, one embodiment of the present invention is 1 to 120
The deviation, the amount of change, and the rate of change with respect to the molecular weight to be maintained in the range of minutes are measured, and the PID operation controller is operated accordingly to automatically control the vacuum. The time is constituted by controlling the molecular weight to be constant by repeating the operation of maintaining the vacuum.

In the present invention, the time interval for measuring the deviation and the rate of change with respect to the molecular weight to be maintained and the time interval until the next pressure change is required to be 1 to 120 minutes. Outside this range, good controllability cannot be obtained.

Specifically, for example, the time interval is 20 minutes,
The molecular weight to be maintained is 15200, the measured molecular weight A at a certain point is 15400, and the measured value 20 minutes before that is 1
Assuming 5300, the deviation is 15400-15200 = 2
00 and the change in 20 minutes is 15400-1530
0 = 100. The change speed is always calculated at one-minute intervals, and the change speed is assumed to be 5 / min. This rate of change is based on a measured molecular weight at some point of 15300,
Assuming that the molecular weight before one minute is 15295, (15300-1
5295) / 1 = 5 / min.

The P setting of the PID calculates a value proportional to the deviation, the I setting calculates a value proportional to the change amount, the D setting calculates a value proportional to the change speed, and calculates P, I, and D. The obtained values are added to calculate the degree of vacuum in the polymerization tank. This degree of vacuum is substituted for the set value of the vacuum regulator of the polymerization tank, and the degree of vacuum is fixed and controlled for the next 20 minutes. Next, when the measured molecular weight A at the 20th minute was 15300, 2
Since the measured value of the molecular weight before 0 minutes is 15400, the deviation P
Is 15300-15200 = 100, the change amount I in 20 minutes is 15300-15400 = -100, and the change speed D is -5 / min, the degree of vacuum of the polymerization tank is calculated by the method described above, and the vacuum The degree of vacuum in the polymerization tank is controlled by substituting it into the set value of the regulator. The setting of the time interval and the PID can be determined by trial and error and is practical. Also,
If the time interval is less than 1 minute, the variation in the molecular weight may diverge with time, which is not preferable. If the time interval exceeds 120, a fluctuation having a long period may appear, which is not preferable.

In the present invention, as a method of controlling the pressure in the reactor, for example, a method of detecting the pressure in the reactor or the pressure in the vapor piping to adjust the opening of the valve for the vacuum source, or a method immediately before the vacuum source A method of adjusting the amount of the inert gas to be blown into the air may be considered. In the present invention, any arbitrary pressure control method can be used without any particular limitation.

The vacuum source used in the present invention is not particularly limited, and any generally available vacuum source 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.

The aromatic polycarbonate referred to in the present invention is a melt polycondensation of an aromatic dihydroxy compound, which is a main component, and a carbonate in the presence of a transesterification catalyst comprising a basic nitrogen compound and an alkali metal compound. It is an aromatic polycarbonate.

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.

Examples of the carbonic acid 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 include, as an aliphatic diol, ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,10-decanediol and the like. 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.

Although the catalyst used in the present invention is not particularly limited, a transesterification catalyst comprising a basic nitrogen compound and an alkali metal compound and / or an alkaline earth metal compound can be used.

The alkali metal and / or alkaline earth metal compound used in the present invention is not particularly limited as long as it does not lower the hue of the aromatic polycarbonate obtained, and various known compounds can be used. it can.

The alkali metal compound used as a 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.

Examples of the alkaline earth metal compound used as a catalyst include hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates and thiocyanates of alkaline earth metals. , Stearates,
Benzoates, bisphenols, phenol salts and the like can be mentioned.

Specific examples include calcium hydroxide, barium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, strontium carbonate, calcium acetate, barium acetate, strontium acetate, Calcium nitrate, barium nitrate, strontium nitrate, calcium nitrite, barium nitrite, strontium nitrite, calcium sulfite, barium sulfite, strontium sulfite, calcium cyanate, barium cyanate, strontium cyanate, calcium thiocyanate, barium thiocyanate, Strontium thiocyanate, calcium stearate, barium stearate, strontium stearate, calcium borohydride, barium borohydride, water Boron strontium, calcium benzoate, barium benzoate, strontium benzoate, calcium salts of bisphenol A, a barium salt,
Strontium salts, calcium salts of phenol, barium salts, strontium salts and the like can be mentioned.

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.

(A) Examples of the alkali metal salt of an ate complex of the Group 14 element of the periodic table include those described in JP-A-7-268091, and specifically, a compound of germanium (Ge); NaGe (OMe) ₅ , NaGe
(OEt) ₅ , 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) ₃ , NaSn (OPh) ₅ , NaSnBu
₂ (OMe) ₃ .

(B) The alkali metal salt of an oxo acid of Group 14 element of the periodic table is, for example, silicic acid (sili)
Cic acid), stannic acid (sta)
alkali metal salt of germanic acid, germanium (II) acid, germanic acid (germanic acid), germanic acid (germanic acid)
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 .X).
_{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 ).

The alkali metal compound or alkaline earth metal compound used as the catalyst is such that the alkali metal element or alkaline earth metal element in the catalyst is 1 × 10 ^{-8 to} 5 × 10 ^-5 equivalent per mole of the aromatic diol compound. It is preferably used in such a ratio. A more preferable ratio is a ratio that is 5 × 10 ⁻⁷ to 1 × 10 ⁻⁵ equivalents with respect to the same standard.

If the amount of the alkali metal element or alkaline earth metal element in the catalyst deviates from the range of 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per 1 mole of the aromatic diol compound, the aromatic polycarbonate obtained is It is not preferable because it has problems such as adversely affecting various physical properties, and insufficient transesterification reaction to obtain a high molecular weight aromatic polycarbonate.

Examples of the nitrogen-containing basic compound as a catalyst include, 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 above-mentioned nitrogen-containing basic compound is a nitrogen-containing basic compound.
Ammonium nitrogen atom in compound is aromatic diol compound
1 × 10 per mole of product^-Five~ 5 × 10^-3At the equivalent ratio
It is preferably used. A more desirable ratio is based on the same criteria.
2 × 10^-Five~ 5 × 10^-FourThis is the equivalent ratio. In particular
The preferred ratio is 5 × 10 for the same standard^-Five~ 5 × 10 ^-Four
This is the equivalent ratio.

In the specification of the present application, the charged aromatic diol compound (also referred to as aromatic dihydroxy compound)
The ratio of the alkali metal compound, the alkaline earth metal compound and the nitrogen-containing basic compound to the ratio of "W
(Numerical value) equivalent Z (compound name) amount "
This is because, for example, if Z is sodium phenoxide or 2,2
If there is one sodium atom, such as -bis (4-hydroxyphenyl) propane monosodium salt, or one basic nitrogen, such as triethylamine, Z
Is an amount corresponding to W moles, and 2,2
If it is two such as -bis (4-hydroxyphenyl) propane disodium salt, it means that the amount is equivalent to W / 2 mol.

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 co-catalysts in a specific ratio, the terminal blocking reaction and the polycondensation reaction rate are not impaired, the branching reaction which is liable to be generated during the polycondensation reaction, or the foreign matter in the apparatus during the molding process is performed. Undesirable side reactions such as generation and burning can be more effectively suppressed.

In the present invention, the temperature and pressure at which the transesterification reaction between the aromatic dihydroxy compound and the carbonic acid diester is not particularly limited, the reaction starts, and the monohydroxy compound produced by the reaction is quickly discharged out of the reaction system. Any conditions may be used as long as the temperature and the pressure are removed, but a temperature of 150 ° C. to 200 ° C. and 4.0 × 10 4
³ Pa (30 mmHg) to 1.333 × 10 ⁴ Pa (10
After the reaction is started at a pressure of 0 mmHg), the reaction temperature is increased and the reaction pressure is decreased according to the increase in the molecular weight of the polycarbonate as the reaction proceeds, and finally the reaction pressure is reduced to 270 to 35.
0 ° C. and 1.333 × 10 ² Pa (1 mmH
g) It is common to carry out the reaction at the following pressures.

More specifically, in the range where the viscosity average molecular weight (Mv) of the polycarbonate is 1000 to 2000, the temperature is 150 to 220 ° C. and the viscosity is 4.0 × 10 ³ Pa (3
0 mmHg) to 1.333 × 10 ⁴ Pa (100 mmHg)
g) The reaction was carried out at a pressure of
In the region of 200-250 ° C., 1.333 × 10 ³ Pa
(10 mmHg) to 1.333 × 10 ⁴ Pa (100 m
mHg), and in the region where Mv exceeds 10,000, at 250 to 300 ° C. and 1.333 × 10 ² Pa (1
mmHg) or less. The unit of pressure used is absolute pressure unless otherwise specified.

In the present invention, there is no particular limitation on equipment and processes used for producing a polycarbonate by transesterifying an aromatic dihydroxy compound and a carbonic acid diester, and conventionally known equipment and processes can be used.

As a continuous-type facility, for example, two or more reactors are installed in series, adjacent reactors are connected by a pipe equipped with a valve, and a facility equipped with a pump for transferring a reaction solution is used. It is carried out by continuously feeding raw materials and catalyst to the first reactor while continuously maintaining different conditions in each reactor, and continuously extracting polycarbonate having a desired molecular weight from the last reactor.

The molar ratio of the carbonic acid diester to the aromatic dihydroxy compound depends on the capacity of the rectification column, the conversion of the monomer in the reactor, and the OH of the polycarbonate to be obtained.
It varies depending on the amount of terminal groups, but is usually from 0.8 to 1.5, preferably from 0.95 to 1.1, more preferably from 1.0 to 1.05.
Is used.

There are no particular restrictions on the material of the equipment used in these facilities, but materials with a high iron content should be avoided, and nickel, stainless steel or the like is usually preferably used.

A catalyst deactivator can be added to the polycarbonate obtained in the present invention.

The catalyst deactivator used in the present invention includes:
Known catalyst deactivators are effectively used. Among them, ammonium salts and phosphonium salts of sulfonic acids are preferable, and the above salts of dodecylbenzenesulfonic acid such as tetrabutylphosphonium salt of dodecylbenzenesulfonic acid and paratoluenesulfonic acid The above salts of paratoluenesulfonic acid such as tetrabutylammonium salt 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 directly added or dissolved or dispersed in an appropriate solvent, and added to the molten polycarbonate and kneaded. 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 these can be used in combination of two or more.

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

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, the additives may be directly added to the polycarbonate, or a master pellet may be prepared and added.

[0065]

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 to continuously produce polycarbonate. In the method, a metering pump is installed immediately after one or more reactors, and the polymer molecular weight on the outlet side of the reactor is continuously measured by installing a differential pressure measuring device and a thermometer downstream of the metering pump, The deviation and the rate of change in maintaining the molecular weight at a constant time in the range of 1 to 120 minutes were measured.
A method for producing a polycarbonate resin in which the operation controller is operated to automatically control the vacuum, and the operation of maintaining the vacuum is repeated at time intervals in the range of 1 to 120 minutes, whereby the stability of the polymer molecular weight can be significantly improved. Can be provided.

[0066]

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.

In the measurement of the viscosity average molecular weight in the examples and comparative examples, the intrinsic viscosity ([η]) of a 0.7 g / dl methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was calculated by the following equation. (Mv) was determined. [Η] = 1.23 × 10 ⁻⁴ × Mv ^0.83

Example 1 Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.02 mol to 1 mol of 2,2-bis (4-hydroxyphenyl) propane, and nitrogen was charged. After the replacement, the mixture was heated and melted at 150 ° C., and the molten mixture was transferred to a raw material storage tank whose temperature was controlled at 150 ° C.

The processes related to the reaction after the raw material storage tank were continuously operated.

The details of the embodiment will be described below.

Using a metering pump from the raw material storage tank, 240
At the rate of kg / hr, the mixture is continuously fed to the first vertical reactor and 2,2-bis (4-hydroxyphenyl)
With respect to 1 mole of propane, 0.5 × 10 ⁻⁶ equivalents of sodium phenoxide and 1 × 10 ⁻⁴ equivalents of tetramethylammonium hydroxide were also continuously added to the reactor.

The first vertical reactor was provided with a rectification column, and the transesterification reaction was continuously advanced while only phenol was distilled out of the reaction system.

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 phenol produced and vaporized in the second-stage reactor and the remaining raw material partially vaporized are continuously rectified by a rectification column attached to the reactor, and then only phenol is distilled out of the reaction system. The transesterification proceeded continuously.

The viscosity average molecular weight of the prepolymer obtained in the second reactor was 6,000 to 6,600. The prepolymer was continuously withdrawn using a gear pump and continuously fed to the final stage polycondensation reactor.

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), and the molecular weight was adjusted using the automatic control of the molecular weight of the present invention.

The polymer obtained in the polycondensation reactor at the final stage is continuously and quantitatively extracted by using a gear pump, and is simultaneously subjected to a differential pressure measurement and a temperature detecting end provided after the gear pump. Pressure and polymer temperature were measured so that the molecular weight of the polymer could be calculated continuously.

The deviation, the amount of change and the rate of change with respect to the molecular weight to be maintained at intervals of 20 minutes are measured, and the PID operation controller is operated accordingly to automatically control the vacuum, and the operation of maintaining the vacuum is performed at intervals of 20 minutes. The molecular weight of the polymer withdrawn from the final polymerization tank was automatically controlled by repeating the above.

As a result of continuous operation for one month, the viscosity average molecular weight of the obtained pellets was maintained at 15200 ± 200, and there was no need for manual adjustment.

Example 2 The procedure was the same as in Example 1 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 pressure difference and the polymer are continuously detected by a differential pressure measuring device and a temperature detecting terminal installed after the gear pump. The temperature was measured so that the molecular weight of the polymer could be calculated continuously and fed continuously to the final stage polycondensation reactor.

The polycondensation reaction was allowed to proceed continuously while all the phenol and the like generated and vaporized in the horizontal single-shaft reactor at the final stage where the prepolymer was fed were 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), and the molecular weight was adjusted using the automatic control of the molecular weight of the present invention.

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.

The vacuum is automatically controlled by operating the PID operation controller in accordance with the molecular weight difference between the inlet and outlet of the reactor calculated continuously at intervals of 20 minutes, and the operation of maintaining the vacuum is repeated at intervals of 20 minutes. The molecular weight of the polymer discharged from the polymerization tank was automatically controlled.

As a result of continuous operation for one month, the viscosity average molecular weight of the obtained pellets was maintained at 15200 ± 100, and there was no need for manual adjustment.

[Comparative Example] The deviation, the amount of change and the rate of change with respect to the molecular weight to be maintained at intervals of 20 minutes were measured.
In response to this, the PID operation controller is operated to change the set value of the vacuum regulator of the polymerization tank, and the operation of maintaining the vacuum is repeated at intervals of 20 minutes, whereby the molecular weight of the polymer extracted from the final polymerization tank is automatically adjusted. Instead of controlling the pressure, the pressure loss is measured by a conventional method, the viscosity of the polymer is determined therefrom, then the molecular weight is calculated in consideration of the effect of temperature, and the reactor is adjusted so that the molecular weight becomes the target molecular weight. The operation was performed in the same manner as in Example 1 except that the operation was performed by controlling the vacuum continuously (the degree of vacuum was controlled substantially at intervals of 1 second or less).

As a result, the viscosity average molecular weight of the pellet obtained on the outlet side of the polymerization tank fluctuated within a range of 15200 ± 500. In order to keep the molecular weight within the range of 15200 ± 200, the operator had to manually adjust the reactor vacuum three times per hour.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Sawaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Prefecture Teijin Co., Ltd. Inside the Iwakuni Research Center (72) Inventor Katsuji Sasaki 2-1 Hinode-cho, Iwakuni-shi, Yamaguchi Prefecture Teijin Shares F-term in the Iwakuni Research Center (reference) 4J029 AA09 BB04A BB04B BB05A BB10A BB10B BB12A BB12B BB13A BB13B BF14A BF14B BH02 DB07 DB11 DB13 HC04A HC05A HC05B KD07 KE05 KJ05 LB09

Claims (4)

[Claims] 1. A method for producing a polycarbonate by a melt polymerization method, which comprises automatically controlling a degree of vacuum D inside a reactor according to a measured value A of a polymer molecular weight at a reactor outlet, wherein the range is from 1 to 120 minutes. By measuring the deviation, the amount of change, and the rate of change between the molecular weight measurement value A and the molecular weight C to be maintained at the time intervals of, and automatically controlling the degree of vacuum D by the PID operation controller in accordance with this, A method for producing a polycarbonate in which a polymer molecular weight at a reactor outlet is controlled. 2. Automatically controlling the degree of vacuum D inside the reactor according to the difference between the measured value of polymer molecular weight A at the outlet of the reactor and the measured value B of polymer molecular weight at the inlet of the reactor.
A method for producing a polycarbonate by a melt polymerization method, wherein a molecular weight measurement value A is obtained at a time interval in the range of 1 to 120 minutes.
The deviation, the amount of change, and the rate of change of the difference between the measured polymer molecular weight B and the measured polymer molecular weight B are measured, and the degree of vacuum C is automatically controlled by the PID operation controller accordingly, thereby controlling the polymer molecular weight at the reactor outlet. Method for producing polycarbonate. 3. The reactor is provided with a metering pump at its outlet or at the inlet and outlet, and a differential pressure measuring device and a thermometer are installed downstream of the metering pump, thereby obtaining a measured value of polymer molecular weight. The method for producing a polycarbonate according to claim 1 or 2, wherein: 4. A reactor, a metering pump provided at an outlet or an inlet and an outlet thereof, and a molecular weight measuring means provided downstream of the metering pump and comprising a differential pressure measuring device and a thermometer; Means for measuring the degree of vacuum inside the reactor and, at time intervals in the range of 1 to 120 minutes, between the measured molecular weight A at the outlet of the reactor and the measured molecular weight C or the measured molecular weight B at the inlet of the reactor. Measure deviation, change amount and change speed,
Control means for automatically controlling the degree of vacuum D by adjusting the PID operation in accordance with the PID operation.