JP5754465B2 - Continuous production method of aromatic polycarbonate - Google Patents

Description

  The present invention relates to a method for continuously producing aromatic polycarbonates, and more particularly to a method for continuously producing aromatic polycarbonates having a plurality of polycondensation steps.

Aromatic polycarbonate is excellent in mechanical properties such as impact resistance, heat resistance, transparency and the like, and is widely used for various mechanical parts, optical disks, automobile parts and the like.
As a method for producing such an aromatic polycarbonate, a method of directly reacting bisphenols such as bisphenol A with phosgene (interface method), a transesterification reaction between a bisphenol such as bisphenol A and a carbonic diester such as diphenyl carbonate. A method of polycondensation reaction (melting method) is known. Especially, the melting method by transesterification has an advantage that an aromatic polycarbonate can be produced at a lower cost than the interface method.

By the way, since aromatic polycarbonate is used for many applications, it is necessary to produce a plurality of types of aromatic polycarbonate. On the other hand, when producing an aromatic polycarbonate by the melting method described above, it is usually done with a production apparatus in which a plurality of reactors are connected in series under reduced pressure, so the reaction conditions such as the starting molar ratio of the starting materials are changed. Then, a switching loss occurs until the desired type of aromatic polycarbonate is obtained.
As a method for reducing such switching loss and quality deterioration, in a production apparatus in which a plurality of reactors are connected, bisphenol A and diphenyl carbonate are polycondensed in the preceding reactor (preliminary polymerization step), and the subsequent polymerization is performed. A method for continuously producing a plurality of types of aromatic polycarbonate by reporting a plurality of condensation reactions (late polymerization step) has been reported (see Patent Document 1).

Japanese Patent Laid-Open No. 2004-026916

The reaction between diphenyl carbonate and bisphenol A is carried out in the presence of a transesterification catalyst using a production apparatus in which a plurality of reactors are connected, as described in Patent Document 1 described above. Since many transesterification catalysts use a small amount of materials and easily dissolve in water, they are often made into an aqueous solution before being supplied to a raw material monomer melt-mixing tank or a subsequent reactor.
However, when a catalyst is supplied in the melt mixing tank or the reactor, troubles of unknown cause may occur that the obtained polymer does not reach the target molecular weight.
For this reason, there have been problems that the operating conditions such as polymerization temperature, polymerization pressure or residence time have to be changed, the quality such as hue is lowered, and a product having a desired molecular weight cannot be obtained.

This invention is made | formed in order to solve the subject in manufacture of the aromatic polycarbonate by such a melting method.
That is, an object of the present invention is to provide a method for continuously producing an aromatic polycarbonate with reduced switching loss and reduced quality in a method for producing a plurality of types of aromatic polycarbonate by a melting method.
Another object of the present invention is to provide an apparatus for producing an aromatic polycarbonate capable of producing a plurality of types of aromatic polycarbonate without causing a switching loss or the like.

Thus, according to the present invention, there is provided a method for continuously producing an aromatic polycarbonate by melt polycondensation by an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester, wherein the aromatic dihydroxy compound is present in the absence of a transesterification catalyst. And / or a raw material preparation step for preparing a raw material molten mixture of carbonic acid diester (hereinafter, sometimes abbreviated as “primary step”), and a raw material molten mixture prepared in the original step using a plurality of reactors. A polycondensation step in which polycondensation is carried out in the presence of a transesterification catalyst, and there are a plurality of polycondensation steps per one of the original preparation steps, and transfer from the original adjustment step to a plurality of polycondensation steps. There is provided a continuous process for producing an aromatic polycarbonate characterized in that a transesterification catalyst is added during or in the initial stage of a polycondensation step.

Here, in the continuous production method of the aromatic polycarbonate to which the present invention is applied, it is preferable to add the transesterification catalyst after filtering it through a filter.
In the continuous process for producing an aromatic polycarbonate to which the present invention is applied, any one or more selected from an aromatic dihydroxy compound, a carbonic acid diester, a terminal terminator, an additive, and a thermoplastic resin after the original preparation step. Is preferably added.
Furthermore, in the continuous production method of the aromatic polycarbonate to which the present invention is applied, it is preferable to produce the same type and / or different types of different aromatic polycarbonates in a plurality of polycondensation steps.

  Moreover, in the continuous manufacturing method of the aromatic polycarbonate to which the present invention is applied, any one or more selected from an aromatic dihydroxy compound, a carbonic acid diester, a terminal terminator, an additive, and a thermoplastic resin after the original preparation step. It is preferable to add after filtering with a filter.

  According to the present invention, switching loss and quality deterioration are reduced in the continuous production of aromatic polycarbonate.

It is a figure which shows an example of the manufacturing apparatus of the aromatic polycarbonate which has a 2 series polycondensation process. It is a figure explaining the manufacturing apparatus of the aromatic polycarbonate which has a polycondensation process 1 series with respect to an original tone process 1 series. It is a figure which shows an example of the manufacturing apparatus of the aromatic polycarbonate which has the original process 1 series which prepares the mixture of a raw material and a catalyst, and the polycondensation process 2 series. It is a figure which shows an example of the manufacturing apparatus of the aromatic polycarbonate which adds the carbonic acid diester filtered with the filter after the original adjustment process.

  The best mode for carrying out the present invention (hereinafter, an embodiment of the present invention) will be described in detail below. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention. The drawings used are for explaining the present embodiment and do not represent the actual size.

(Aromatic polycarbonate)
In the present invention, the aromatic polycarbonate is produced by polycondensation based on an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester. The polycondensation reaction is performed in a production apparatus having a plurality of polymerization series after preparing an aromatic dihydroxy compound and a carbonic acid diester as raw materials, and one or a plurality of quality aromatic polycarbonates are produced at the same time.
Hereinafter, a method for producing an aromatic polycarbonate by using an aromatic dihydroxy compound and a carbonic acid diester as raw materials and performing a polycondensation reaction in the presence of a transesterification catalyst will be described.

(Aromatic dihydroxy compounds)
Examples of the aromatic dihydroxy compound used in the present embodiment include compounds represented by the following general formula (1).

  Here, in the general formula (1), A is a single bond or an optionally substituted linear, branched or cyclic divalent hydrocarbon group having 1 to 10 carbon atoms, or -O-, A divalent group represented by -S-, -CO- or -SO2-. X and Y are a halogen atom or a C1-C6 hydrocarbon group. p and q are integers of 0 or 1. X and Y and p and q may be the same or different from each other.

Specific examples of the aromatic dihydroxy compound include, for example, bis (4-hydroxydiphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxy-3-methylphenyl) propane. 2,2-bis (4-hydroxy-3-tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3) , 5-dibromophenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, bisphenols such as 1,1-bis (4-hydroxyphenyl) cyclohexane; 4,4′-dihydroxybiphenyl, 3,3 ′ , 5,5'-tetramethyl-4,4'-dihydroxybiphenyl and the like; bis (4-hydroxyphenyl) sulfo Bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone and the like.
Among these, 2,2-bis (4-hydroxyphenyl) propane (“bisphenol A”, hereinafter sometimes abbreviated as BPA) is preferable. These aromatic dihydroxy compounds can be used alone or in admixture of two or more.

(Carbonated diester)
Examples of the carbonic acid diester used in the present embodiment include compounds represented by the following general formula (2).

Here, in general formula (2), A 'is a C1-C10 linear, branched or cyclic monovalent hydrocarbon group which may be substituted. Two A ′ may be the same or different from each other.
In addition, as a substituent on A ′, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, Examples thereof include a nitro group.

Specific examples of the carbonic acid diester include substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate, and dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, and di-t-butyl carbonate.
Among these, diphenyl carbonate (hereinafter sometimes abbreviated as DPC) and substituted diphenyl carbonate are preferable. These carbonic acid diesters can be used alone or in admixture of two or more.

Moreover, said carbonic acid diester may substitute the quantity of the 50 mol% or less preferably 30 mol% or less with the dicarboxylic acid or dicarboxylic acid ester preferably.
Typical dicarboxylic acids or dicarboxylic acid esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate, and the like. When such a dicarboxylic acid or dicarboxylic acid ester is used in combination, polyester carbonate is obtained.

These carbonic acid diesters (including the above-mentioned substituted dicarboxylic acid or dicarboxylic acid ester acid, the same shall apply hereinafter) are used in excess relative to the dihydroxy compound.
That is, it is normally used in a molar ratio of carbonic acid diester of 1.0 to 1.3 with respect to the aromatic dihydroxy compound. Under the same reaction conditions, the reaction rate increases as the molar ratio decreases, and the viscosity average molecular weight of the aromatic polycarbonate tends to increase. Further, when the molar ratio is increased in this range, the reaction rate is decreased and the viscosity average molecular weight tends to be decreased.
If the molar ratio is excessively small, the amount of terminal OH groups of the aromatic polycarbonate obtained by polycondensation increases, and the reactivity increases, but the thermal stability, hydrolysis resistance and the like tend to decrease. Moreover, when the molar ratio is excessively large, it tends to be difficult to produce an aromatic polycarbonate having a desired molecular weight.

(Transesterification catalyst)
Examples of the transesterification catalyst used in the present embodiment include a catalyst usually used for producing an aromatic polycarbonate by a transesterification method, and are not particularly limited. In general, examples include basic compounds such as alkali metal compounds, beryllium or magnesium compounds, alkaline earth metal compounds, basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds.
Among these transesterification catalysts, an alkali metal compound is practically desirable. These transesterification catalysts may be used alone or in combination of two or more.
The transesterification catalyst is generally used in an amount of 1 × 10 ⁻⁹ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻² mol, relative to 1 mol of the aromatic dihydroxy compound. It is done.

Examples of the alkali metal compound include inorganic alkali metal compounds such as alkali metal hydroxides, carbonates and hydrogencarbonate compounds; organic alkali metal compounds such as salts with alkali metal alcohols, phenols and organic carboxylic acids. It is done. Here, examples of the alkali metal include lithium, sodium, potassium, rubidium, and cesium.
Among these alkali metal compounds, cesium compounds are preferable, and cesium carbonate, cesium hydrogen carbonate, and cesium hydroxide are particularly preferable.

  Examples of beryllium or magnesium compounds and alkaline earth metal compounds include inorganic alkaline earth metal compounds such as beryllium, magnesium, hydroxides and carbonates of alkaline earth metals; alcohols of these metals, phenols, organic And salts with carboxylic acids. Here, examples of the alkaline earth metal include calcium, strontium, and barium.

  Examples of basic boron compounds include sodium salts, potassium salts, lithium salts, calcium salts, magnesium salts, barium salts, strontium salts, and the like of boron compounds. Here, as the boron compound, for example, tetramethylboron, tetraethylboron, tetrapropylboron, tetrabutylboron, trimethylethylboron, trimethylbenzylboron, trimethylphenylboron, triethylmethylboron, triethylbenzylboron, triethylphenylboron, tributyl Examples include benzylboron, tributylphenylboron, tetraphenylboron, benzyltriphenylboron, methyltriphenylboron, and butyltriphenylboron.

  Examples of the basic phosphorus compound include trivalent phosphine compounds such as triethylphosphine, tri-n-propylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, and tributylphosphine, or derivatives thereof. And quaternary phosphonium salts.

  Examples of the basic ammonium compound include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethylethylammonium hydroxide, trimethylbenzylammonium hydroxide, trimethylphenylammonium hydroxide, Triethylmethylammonium hydroxide, triethylbenzylammonium hydroxide, triethylphenylammonium hydroxide, tributylbenzylammonium hydroxide, tributylphenylammonium hydroxide, tetraphenylammonium hydroxide, benzyltriphenylammonium hydroxide, methyltol Phenyl ammonium hydroxide, butyltriphenyl ammonium hydroxide, and the like.

  Examples of amine compounds include 4-aminopyridine, 2-aminopyridine, N, N-dimethyl-4-aminopyridine, 4-diethylaminopyridine, 2-hydroxypyridine, 2-methoxypyridine, 4-methoxypyridine, 2 -Dimethylaminoimidazole, 2-methoxyimidazole, imidazole, 2-mercaptoimidazole, 2-methylimidazole, aminoquinoline and the like.

(Continuous production method of aromatic polycarbonate)
Next, the continuous manufacturing method of the aromatic polycarbonate to which this Embodiment is applied is demonstrated.
In the present embodiment, the production of the aromatic polycarbonate is carried out by preparing a mixture of the aromatic dihydroxy compound and the carbonic acid diester compound as raw materials in a desired molar ratio in the absence of a transesterification catalyst (original preparation process). Is carried out by a multi-stage polycondensation reaction (polycondensation step) using a plurality of reactors in a molten state in the presence of a transesterification catalyst by a production apparatus having a plurality of polycondensation steps. The reaction system may be any of a batch system, a continuous system, or a combination of a batch system and a continuous system. As the reactor, a plurality of vertical reactors and then at least one horizontal reactor are used. Usually, these reactors are installed in series and processed continuously.
After the polycondensation step, unreacted raw materials and reaction byproducts in the reaction solution are removed (devolatilization step), and the cooled aromatic polycarbonate is formed into pellets having a predetermined particle size (pelletization step).

In the present embodiment, any one or more selected from an aromatic dihydroxy compound, a carbonic acid diester, a transesterification catalyst, a terminal terminator, an additive, and a thermoplastic resin may be added after the original preparation step. preferable.
Specifically, aromatic dihydroxy compounds, carbonic acid diesters, and transesterification catalysts are added during the transfer from the original process to the polycondensation process, or at the initial stage of the polycondensation process. It is preferable in terms of adjustment.
Moreover, it is suitable for the addition purpose to add a terminal terminator and an additive at the time of the final stage of a polycondensation process, the transfer from a polycondensation process to a devolatilization process, or the initial stage of a devolatilization process.
The timing of adding the thermoplastic resin is not particularly limited, but when performing the devolatilization process using an extruder, it is generally added in this process.

In this case, these compounds are preferably added after the original preparation step after being filtered by a predetermined filter.
Here, as a form of the filter, generally known ones such as a candle type, a pleat type and a leaf disk type can be used, and are not particularly limited. The material of the filter is not particularly limited as long as it is inactive to the above-described compound and has no elution component, but usually a metal, particularly stainless steel is used. For example, SUS304, SUS316, etc. are preferably used. .
The opening of the filter to be used is not particularly limited, but usually the absolute filtration accuracy is 0.5 μm to 50 μm, preferably 0.5 μm to 20 μm. The absolute filtration accuracy means a particle diameter at which the removal rate is 99% or more when particles are passed through a filter.

In addition, when adding carbonic acid diester filtered through a predetermined filter after the original preparation step, the raw material molar ratio of carbonic acid diester to aromatic dihydroxy compound in the whole raw material mixture (carbonic acid diester / aromatic dihydroxy compound) in advance. Is a predetermined numerical value (set raw material) selected from a range of 1.0 to 1.3, preferably 1.00 to 1.30, more preferably 1.001 to 1.300. Molar ratio). In addition, in the steps after the original preparation step, it is preferable to additionally add the carbonic acid diester so that the raw material molar ratio between the carbonic acid diester and the aromatic dihydroxy compound becomes a preset raw material molar ratio. In this case, it is preferable to maintain the accuracy of fluctuation of the set raw material molar ratio within a range of ± 0.8.
Next, each process of the manufacturing method will be described.

(Primary process)
The aromatic dihydroxy compound and carbonic acid diester used as the raw material for the aromatic polycarbonate are usually used in a batch, semi-batch or continuous stirring tank type apparatus in an atmosphere of an inert gas such as nitrogen or argon. Prepared as a molten mixture in the absence of a transesterification catalyst. For example, when bisphenol A is used as the aromatic dihydroxy compound and diphenyl carbonate is used as the carbonic acid diester, the temperature of the melt mixing is usually selected from the range of 120 ° C to 180 ° C, preferably 125 ° C to 160 ° C.
At this time, the ratio of the aromatic dihydroxy compound and the carbonic acid diester is adjusted so that the carbonic acid diester becomes excessive, and the carbonic acid diester is usually 1.01 mol to 1.30 mol with respect to 1 mol of the aromatic dihydroxy compound. Preferably, it is adjusted to a ratio of 1.02 mol to 1.20 mol.

(Polycondensation process)
The polycondensation by the transesterification reaction between the aromatic dihydroxy compound and the carbonic acid diester compound is usually carried out continuously in a multistage system of 2 or more stages, preferably 3 to 7 stages in each series. Specific reaction conditions are temperature: 150 ° C. to 320 ° C., pressure: normal pressure to 0.01 Torr (1.33 × 10 ⁻³ kPa), and average residence time: 5 minutes to 150 minutes.
In each reactor when the polycondensation step is performed in a multi-stage system, in order to more effectively discharge the by-product phenol as the polycondensation reaction proceeds, the reaction conditions are usually higher, in stages, Set to a higher vacuum. In order to prevent quality deterioration of the hue and the like of the aromatic polycarbonate obtained, it is preferable to set the temperature and the residence time as low as possible.

When the polycondensation step is performed in a multistage manner, usually, a plurality of vertical reactors and / or at least one horizontal reactor following the same are provided to increase the average molecular weight of the polycarbonate resin. Usually, 3 to 6 reactors, preferably 4 to 5 reactors are installed.
Here, as a reactor, for example, a stirred tank reactor, a thin film reactor, a centrifugal thin film evaporation reactor, a surface renewal type biaxial kneading reactor, a biaxial horizontal type stirring reactor, a wet wall reactor, a free reactor A perforated plate reactor that polymerizes while dropping, a perforated plate reactor with wire that polymerizes while dropping along a wire, and the like are used.

  Examples of the type of agitator blades in the vertical reactor include turbine blades, paddle blades, fiddler blades, anchor blades, full zone blades (manufactured by Shinko Pantech Co., Ltd.), Sunmeler blades (manufactured by Mitsubishi Heavy Industries, Ltd.), and Max Blend blades. (Sumitomo Heavy Industries, Ltd.), helical ribbon wing, twisted lattice wing (Hitachi, Ltd.), and the like.

  Moreover, a horizontal reactor means that the rotating shaft of a stirring blade is a horizontal type (horizontal direction). As a stirring blade of a horizontal reactor, for example, a single-shaft type stirring blade such as a disk type or a paddle type, HVR, SCR, N-SCR (manufactured by Mitsubishi Heavy Industries, Ltd.), viola rack (manufactured by Sumitomo Heavy Industries, Ltd.) Or a twin-shaft type stirring blade such as a spectacle blade or a lattice blade (manufactured by Hitachi, Ltd.).

In addition, the transesterification catalyst used for the polycondensation of the aromatic dihydroxy compound and the carbonic acid diester compound is usually prepared in advance as an aqueous solution. The concentration of the catalyst aqueous solution is not particularly limited, and is adjusted to an arbitrary concentration according to the solubility of the catalyst in water. Moreover, it can replace with water and other organic solvents, such as acetone, alcohol, toluene, and phenol, can also be used.
The properties of water used for dissolving the catalyst are not particularly limited as long as the type and concentration of impurities contained are constant, but usually distilled water, deionized water, and the like are preferably used.

(Devolatilization process)
After the polycondensation step in each series, low molecular weight compounds such as unreacted raw materials, transesterification catalyst, hydroxy compounds by-produced in the transesterification reaction, and polycarbonate oligomers are removed in the devolatilization step. The devolatilization process is usually performed continuously by a vent type extruder.
The extruder to be used is not particularly limited as long as it is equipped with a vent portion, and examples thereof include, but are not limited to, a vent type single-screw or multi-screw extruder, In particular, a meshing type twin screw extruder is preferable. The rotation direction of the shaft of the extruder may be the same direction or a different direction. The number of vents is usually a multistage vent of 2 to 10 stages.

Further, in the devolatilization step, it is preferable to neutralize and deactivate the residual basic transesterification catalyst in the aromatic polycarbonate after the polycondensation reaction with a terminal terminator such as an acidic compound or a derivative thereof. Thereby, the side reaction during devolatilization can be suppressed, and the remaining unreacted raw material and hydroxy compound can be removed.
Any acidic compound or derivative thereof added in the devolatilization step can be used as long as it neutralizes the basic transesterification catalyst, and is not particularly limited. For example, hydrochloric acid, nitric acid, boric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, adipic acid, ascorbic acid, aspartic acid, azelaic acid, adenosine phosphoric acid, benzoic acid, formic acid, yoshiyoshi Herbic acid, citric acid, glycolic acid, glutamic acid, glutaric acid, cinnamic acid, succinic acid, acetic acid, tartaric acid, oxalic acid, p-toluenesulfinic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, nicotinic acid, picric acid, picoline Examples thereof include Bronsted acids such as acid, phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid, maleic acid, and esters thereof. These acidic compounds or derivatives thereof may be used alone or in combination of two or more. Among these acidic compounds or derivatives thereof, sulfonic acids or esters thereof are preferable, and p-toluenesulfonic acid, methyl p-toluenesulfonate, butyl p-toluenesulfonate, and the like are particularly preferable.

  The solvent that dissolves the acidic compound or derivative thereof is not particularly limited as long as it dissolves the acidic compound or derivative thereof. Of these, water is preferable. Moreover, the acidic compound insoluble in water or its derivative (s) can use the mixed solvent which added organic solvents, such as acetone, to water. The use amount of these acidic compounds or derivatives thereof is 0.1 to 50 times, preferably 0.5 to 30 times the neutralization equivalent of the basic transesterification catalyst used in the polycondensation reaction. .

  In the devolatilization step, when using an extruder equipped with a multistage vent port, the acidic compound or derivative thereof is usually added before the vent port closest to the resin supply port. As a form of the aromatic polycarbonate to be subjected to neutralization devolatilization treatment by an extruder, a method of introducing it into an extruder while being in a molten state immediately after polymerization, or a method of once cooling and solidifying and then introducing into an extruder and processing And the like.

(Pelletization process)
The strand-like aromatic polycarbonate discharged from the extruder in the devolatilization step is usually pelletized by a strand cutter via a strand bath, and then stored in a product silo after removing water by a centrifugal dehydrator or the like. .

(Aromatic polycarbonate production equipment)
Next, a method for continuously producing an aromatic polycarbonate to which the present embodiment is applied will be described with reference to the drawings.
FIG. 1 is a diagram showing an example of an apparatus for producing an aromatic polycarbonate having two series of polycondensation steps. In the production apparatus shown in FIG. 1, two kinds of aromatic polycarbonates having different qualities are prepared in one original process for preparing a mixture containing a raw material aromatic dihydroxy compound and a carbonic acid diester compound in the absence of a transesterification catalyst, These raw materials are produced through two series of polycondensation processes (first series polycondensation process and second series polycondensation process) in which these raw materials are polycondensed using a plurality of reactors in a molten state.
And then, a devolatilization process (first series devolatilization process, second series devolatilization process) for removing unreacted raw materials and reaction by-products in the polymerization reaction solution, and a pelletization process (first series pelletization process, Through the second series pelletization step, two types of aromatic polycarbonate pellets are produced.

In the present embodiment, using a raw material mixture prepared in one raw preparation step of preparing a raw material in the absence of a transesterification catalyst, and then in two series (first series, second series) polycondensation, It is characterized in that a polycondensation reaction of an aromatic dihydroxy compound and a carbonic acid diester compound is performed under different polymerization conditions.
Subsequent to one original preparation step for preparing a raw material in the absence of a transesterification catalyst, two series of polycondensation steps produce aromatic polycarbonate of each quality for each series.
By performing the polycondensation reaction of the aromatic dihydroxy compound and the carbonic acid diester compound in the two series of polycondensation, the problem of switching loss and quality deterioration during production using a production apparatus having a single polycondensation step is solved, For example, a plurality of aromatic polycarbonates having different average molecular weights and terminal group numbers can be continuously produced stably and efficiently.

Next, the structure of the aromatic polycarbonate manufacturing apparatus will be described.
As shown in FIG. 1, in the original conditioning process, a first raw material mixing tank 2 a and a second raw material mixing tank 2 b connected in series as melt mixing tanks are provided. Also, there are raw material supply pumps 4a and 4b for supplying the prepared raw materials to two series (first series, second series) polycondensation steps (first series polycondensation step, second series polycondensation step), respectively. Is provided. For example, anchor-type stirring blades 3a and 3b are provided in the first raw material mixing tank 2a and the second raw material mixing tank 2b, respectively.

  A carbonic acid diester compound and an aromatic dihydroxy compound are used as a raw material for the aromatic polycarbonate. In order to prepare the raw material mixture supplied to a polycondensation process, these are each continuously introduce | transduced into the 1st raw material mixing tank 2a from a raw material supply port. Since these raw material compounds are usually solid at normal temperature, at least one of the raw materials is introduced by heating and melting in advance.

Of the two raw materials, the carbonic acid diester compound generally has a lower melting point than the aromatic dihydroxy compound, and is easily decomposed when the aromatic dihydroxy compound is melted. The aromatic dihydroxy compound is introduced as a solid.
In the present embodiment, diphenyl carbonate (hereinafter sometimes referred to as DPC), which is a carbonic acid diester, is supplied to the first raw material mixing tank 2a from the DPC supply port 1a-1 in a melted state. Bisphenol A, which is an aromatic dihydroxy compound (hereinafter sometimes referred to as BPA), is supplied in powder form from the supply port 1b.

  Next, the polycondensation process having two series will be described. In the first series polycondensation step of the first series, a first vertical reactor 6a and a second vertical reactor each having max blend blades 7a, 7b, 7c, which are polycondensation reactors, connected in series. 6b and a third vertical reactor 6c, and a fourth horizontal reactor 9a having a lattice blade 10a are provided. By-product discharge pipes 8a, 8b, 8c and 81 are attached to the four reactors, respectively. Each of these by-product discharge pipes is connected to a condenser (not shown), and each reactor is kept in a predetermined reduced pressure state by a decompression device (not shown).

Next, in the first series devolatilization step, an extruder 11a having additive supply ports 12a, 12b, and 12c is provided.
In the first series pelletizing step, a strand bath 13a for cooling the strand-like aromatic polycarbonate discharged from the extruder 11a, a strand cutter 14a for cutting the cooled strand into a predetermined particle diameter, and moisture of the pellets A centrifugal dehydrator 15a for removal and product silos 16a and 16b for storing dried pellets are provided.

  Similarly to the first series described above, the second series includes the first vertical reactor 6d and second series connected to each other in the second series polycondensation step, each having a max blend blade 7d, 7e, 7f. A vertical reactor 6e and a third vertical reactor 6f, and a fourth horizontal reactor 9b having lattice blades 10b are provided. By-product discharge pipes 8d, 8e, 8f, and 82 are attached to the four reactors, respectively, and are connected to condensers (not shown), and each reactor is connected to a decompression device (not shown). A predetermined reduced pressure state is maintained.

Next, in the second series devolatilization step, an extruder 11b having additive supply ports 12d, 12e, and 12f is provided.
In the second series pelletizing step, a strand bath 13b, a strand cutter 14b, a centrifugal dehydrator 15b, and product silos 16c and 16d are provided.

Next, steps for producing an aromatic polycarbonate in the aromatic polycarbonate production apparatus shown in FIG. 1 will be described.
As shown in FIG. 1, the DPC melt prepared at a predetermined temperature in the nitrogen gas atmosphere and the BPA powder measured in the nitrogen gas atmosphere in the primary conditioning step are respectively connected to the DPC supply port 1 a-1 and the BPA. It is continuously supplied from the supply port 1b to the first raw material mixing tank 2a. Then, the DPC melt and the BPA powder are mixed in the first raw material mixing tank 2a in the absence of the transesterification catalyst. When the liquid level of the first raw material mixing tank 2a exceeds the same height as the highest level in the transfer pipe, the raw material mixture is transferred to the second raw material mixing tank 2b and further stirred and mixed.

Next, the raw material mixture is continuously supplied to the first series first vertical reactor 6a via the raw material supply pump 4a. Further, it is also continuously supplied to the first vertical reactor 6d of the second series via the raw material supply pump 4b.
In the first series, a DPC melt prepared at a predetermined temperature is supplied from a DPC supply port 1a-2 provided in the middle of a transfer pipe connecting the raw material supply pump 4a and the first vertical reactor 6a. Supplied.

In the first series, by supplying the DPC melt from the DPC supply port 1a-2, the molar ratio of the (DPC / BPA) mixture prepared in the above-described original preparation step is changed as necessary, and an arbitrary quality is obtained. Aromatic polycarbonate can be polycondensed.
The DPC melt supply port is not limited to being provided in front of the first vertical reactor 6a. For example, the DPC melt supply port is provided between the first vertical reactor 6a and the second vertical reactor 6b, It may be provided as necessary, such as in the middle between the type reactor 6b and the third vertical reactor 6c. Further, the number of DPC melt supply ports is appropriately selected as necessary.
Further, in the second series to be described later, similarly to the first series, a predetermined DPC supply port is provided and a DPC melt is supplied to thereby prepare a mole of the (DPC / BPA) mixture prepared in the above-described original preparation process. The ratio can be adjusted as needed.

  Further, in the first series, cesium carbonate in the form of an aqueous solution as a transesterification catalyst is continuously supplied from a catalyst supply port 5a provided in front of the first vertical reactor 6a in the transfer pipe. Similarly, in the 2nd system, it supplies continuously from the catalyst supply port 5b provided in front of the 1st vertical reactor 6d in transfer piping.

In the continuous production method of the aromatic polycarbonate to which the present embodiment is applied, the raw material and the transesterification catalyst are not brought into contact with each other in the first raw material mixing tank 2a and the second raw material mixing tank 2b in the original process (DPC / BPA) mixture is prepared, and then, in a plurality of series polycondensation steps, a transesterification catalyst is supplied to each series to proceed with a polycondensation reaction.
The amount of the transesterification catalyst supplied to each series of the multiple series polycondensation steps is appropriately selected according to the quality of the aromatic polycarbonate produced in each series, and is not particularly limited. Further, the number of transesterification catalyst supply ports is not limited. For example, a plurality of catalyst supply ports may be provided and the transesterification catalyst may be divided and supplied.
Further, in the second series described later, as in the first series, a predetermined catalyst supply port can be provided to supply the transesterification catalyst.

Subsequently, the first series polycondensation step will be described, and the code of the second series is shown in parentheses. In the first vertical reactor 6a (6d), for example, a temperature of 220 ° C., a pressure of 13.33 kPa (100 Torr) and a blade rotation speed of 160 rpm are maintained in a nitrogen atmosphere, and by-produced phenol is by-produced discharge pipe 8a (8d). The polycondensation reaction is carried out while keeping the liquid level constant so that the average residence time is 60 minutes. Next, the polymerization reaction liquid discharged from the first vertical reactor 6a (6d) continues to the second vertical reactor 6b (6e), the third vertical reactor 6c (6f), the fourth horizontal reaction. The polycondensation reaction proceeds sequentially and continuously to the vessel 9a (9b). The reaction conditions in each reactor are set so as to become high temperature, high vacuum, and low stirring speed as the polycondensation reaction proceeds. During the polycondensation reaction, the liquid surface level is controlled so that the average residence time in each reactor is, for example, about 60 minutes. In each reactor, by-product phenol is discharged as by-product discharge pipes 8b and 8c. , 81 (8e, 8f, 82).
In the present embodiment, byproducts such as phenol are present from condensers (not shown) attached to the first vertical reactor 6a (6d) and the second vertical reactor 6b (6e), respectively. Liquefied and recovered continuously. In addition, a condenser (not shown) attached to each of the third vertical reactor 6c (6f) and the fourth horizontal reactor 9a (9b) is provided with a cold trap (not shown). Is continuously solidified and recovered.

  Next, the aromatic polycarbonate extracted from the fourth horizontal reactor 9a (9b) is supplied to a biaxial extruder 11a (11b) having a three-stage vent port in a molten state. For example, butyl p-toluenesulfonate and tris (2,4-di-t-butylphenyl) phosphite are supplied to the extruder 11a (11b) from the additive supply ports 12a, 12b, 12c (12d, 12e, 12f). Various additives such as stearic acid monoglyceride are supplied. The conditions of the extruder 11a are set, for example, to a discharge rate of 50 kg / h, a rotation speed of 150 rpm, and a maximum resin temperature of about 278 ° C.

In this embodiment, for example, other thermoplastic resins other than the aromatic polycarbonate are supplied from the additive supply ports 12a, 12b, 12c (12d, 12e, 12f) of the extruder 11a (11b), Polymer alloys and the like can be prepared.
Next, the strand-like aromatic polycarbonate discharged from the extruder 11a (11b) is pelletized by the strand cutter 14a (14b) via the strand bath 13a (13b), and is centrifuged by the centrifugal dehydrator 15a (15b). After removing the water, it is introduced into the product silos 16a and 16b (16c and 16d).

As described above, in the present embodiment, a method for producing aromatic polycarbonates having different qualities in a production apparatus having two series of polycondensation steps following one original preparation step for preparing a raw material in the absence of a transesterification catalyst. As described in detail above, the number of polycondensation steps can be further increased as necessary.
In the present embodiment, an example in which two types of aromatic polycarbonates having different varieties are produced simultaneously in two series of polycondensation steps has been described. However, if necessary, two series of polycondensation steps are used. It is also possible to produce the same kind of aromatic polycarbonate in parallel.

Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to a following example, unless it deviates from the summary.
(1) Viscosity average molecular weight of aromatic polycarbonate (Mv)
The viscosity average molecular weight (Mv) of the aromatic polycarbonate was determined from the following equation by measuring the intrinsic viscosity [η] at 20 ° C. in methylene chloride using an Ubbelohde viscometer.
[Η] = 1.23 × 10 −4 × (Mv) ^0.83
(2) Terminal hydroxyl group concentration of aromatic polycarbonate The terminal hydroxyl group concentration of aromatic polycarbonate is measured by colorimetric determination in accordance with the titanium tetrachloride / acetic acid method (see Makromol. Chem. 88, 215 (1965)). did.
(3) Hue of the aromatic polycarbonate The hue of the aromatic polycarbonate was molded under conditions of a barrel temperature of 280 ° C. and a mold temperature of 90 ° C. using an injection molding machine (J100SS-2 manufactured by Nippon Steel Works). For a sheet with a thickness of 3 mm and a side of 100 mm square, the tristimulus value XYZ, which is the absolute value of the color, is measured with a color tester (SC-1-CH, manufactured by Suga Test Instruments Co., Ltd.). A certain YI value was calculated.
YI = (100 / Y) × (1.28X−1.06Z)
The larger the YI value, the more colored it is.

Example 1
As shown in FIG. 1, an aromatic polycarbonate was produced as follows using an apparatus for producing an aromatic polycarbonate having two series of polycondensation steps.
(Raw material solution preparation)
The DPC melt prepared at 120 ° C. under a nitrogen gas atmosphere and the BPA powder weighed under the nitrogen gas atmosphere were supplied to the first raw material mixing tank 2a from the DPC supply port 1a-1 and the BPA supply port 1b, respectively. DPC was weighed with a micromotion flow meter and a loss-in-weight weight feeder so that the feed rate was 87.7 kg / h and the BPA was feed rate 89.8 kg / h (DPC / BPA molar ratio 1.040). . The first raw material mixing tank 2a is set to 140 ° C. under an atmospheric pressure nitrogen atmosphere, has an internal volume of 0.4 m ³ , and includes an anchor type stirring blade 3a. At this time, there is no transesterification catalyst in the first raw material mixing tank 2a.

When the liquid level of the first raw material mixing tank 2a exceeds the same height as the highest position in the transfer pipe (that is, corresponding to the internal volume of 0.26 m ³ of the first raw material mixing tank 2a), the raw material mixture becomes the second. It is transferred to the raw material mixing tank 2b. The second raw material mixing tank 2b is set to 140 ° C. under an atmospheric pressure nitrogen atmosphere, has an internal volume of 0.4 m ³ , and includes an anchor type stirring blade 3b.
The total residence time of the raw material mixture required to pass through the first raw material mixing tank 2a and the second raw material mixing tank b was 160 minutes. The raw material mixture did not undergo transesterification, and the BPA reaction rate was 0%.

(Polycondensation reaction)
Next, the raw material mixture is passed through the raw material supply pumps 4a and 4b, respectively, and (1/2) of the raw material mixture at the same flow rate (88.8 kg / h) is converted into the first series first vertical reactor 6a. And the first vertical reactor 6d of the second series were respectively fed continuously. The first vertical reactor 6a and the first vertical reactor 6d are each provided with Max Blend blades 7a and 7d and have an internal volume of 0.1 m ³ .

At the same time, the first series has a (DPC / BPA) molar ratio of the entire raw material mixture from the DPC supply port 1a-2 in which a DPC melt prepared at 120 ° C. in a nitrogen gas atmosphere is provided in the middle of the raw material mixture transfer pipe. It was supplied at a flow rate of 1.03 kg / h so as to be 1.065.
Further, as the transesterification catalyst, an aqueous cesium carbonate solution (concentration: 0.011%) is supplied from the catalyst supply port 5a provided behind the DPC supply port 1a-2 of the raw material mixture transfer pipe in the first system, From the catalyst supply port 5b provided immediately before the first vertical reactor 6d of the transfer pipe, 204 ml / h (0.35 × 10 ⁻⁶ mol with respect to 1 mol of BPA) and 292 ml / h (with respect to 1 mol of BPA), respectively. 0.50 × 10 ⁻⁶ mol).

(First series)
The first vertical reactor 6a of the first series is maintained at a temperature of 220 ° C., a pressure of 13.33 kPa (100 Torr) and a blade rotation speed of 160 rpm in a nitrogen atmosphere, and by-produced phenol is distilled from the by-product discharge pipe 8a. The liquid level was kept constant so that the average residence time was 60 minutes.
The polymerization reaction liquid discharged from the first vertical reactor 6a continues to be the second vertical reactor 6b, the third vertical reactor 6c, and the lattice blade 10a having an internal volume of 0.1 m ^{3 and} having the Max blend blade 7b. Were successively supplied to a fourth horizontal reactor 9a having an internal volume of 0.15 m ³ .
The polycondensation reaction conditions in the second vertical reactor 6b to the fourth horizontal reactor 9a were set to the following conditions so as to become high temperature, high vacuum, and low stirring speed as the reaction progressed.

Second vertical reactor 6b; temperature 240 ° C., pressure 2.00 kPa (15 Torr), blade rotation speed 131 rpm
Third vertical reactor 6c; temperature 260 ° C., pressure 0.09 kPa (0.7 Torr), blade rotation speed 44 rpm
Fourth horizontal reactor 9a; temperature 265 ° C., pressure 0.09 kPa (0.7 Torr), blade rotation speed 5 rpm

During the polycondensation reaction in each reactor, the liquid level was controlled so that the average residence time of each reactor was 60 minutes. Further, phenol produced as a by-product in each reactor was distilled off.
The aromatic polycarbonate extracted from the fourth horizontal reactor 9a is a two-screw extruder 11a (manufactured by Kobe Steel, Ltd., screw diameter 0.046 m, L / D) provided with a three-stage vent port in a molten state. = 36). To the extruder 11a, butyl p-toluenesulfonate, tris (2,4-di-t-butylphenyl) phosphite and stearic acid monoglyceride were supplied from additive supply ports 12a, 12b and 12c, respectively. The supply amounts of these compounds were quantitatively supplied to the aromatic polycarbonate at concentrations of 5 ppm, 50 ppm and 350 ppm, respectively.
The extrusion conditions of the extruder 11a were a discharge rate of 50 kg / h, a rotation speed of 150 rpm, and a maximum resin temperature of 278 ° C.

The strand-like aromatic polycarbonate discharged from the extruder 11a was pelletized with a strand cutter 14a via a strand bath 13a, and after removing water with a centrifugal dehydrator 15a, it was introduced into product silos 16a and 16b. In the product silos 16a and 16b, aromatic polycarbonates having the following physical properties were continuously stored.
Viscosity average molecular weight (Mv); 14,800
Terminal hydroxyl group concentration: 790 ppm
YI (yellowness) = 1.5

(Second series)
Next, the first vertical reactor 6d in the second series is maintained under a nitrogen atmosphere at a temperature of 220 ° C., a pressure of 13.33 kPa (100 Torr), a blade rotation speed of 160 rpm, and by-produced phenol as a by-product discharge pipe 8d. The liquid level was kept constant so that the average residence time was 60 minutes.
The polymerization reaction liquid discharged from the first vertical reactor 6d is continuously supplied to the second vertical reactor 6e, the third vertical reactor 6f, and the lattice blade 10b having an internal volume of 0.1 m ³ provided with the Max blend blade 7e. This was successively supplied continuously to the fourth horizontal reactor 9b having an internal volume of 0.15 m ³ .
As in the first series described above, the polycondensation reaction conditions in the second vertical reactor 6e to the fourth horizontal reactor 9b are as follows so that the high temperature, high vacuum, and low stirring speed are achieved as the reaction proceeds. Set to.

Second vertical reactor 6e; temperature 240 ° C., pressure 2.00 kPa (15 Torr), blade rotation speed 131 rpm
Third vertical reactor 6f; temperature 270 ° C., pressure 0.13 kPa (1.0 Torr), blade rotation speed 44 rpm
Fourth horizontal reactor 9b; temperature 280 ° C., pressure 0.13 kPa (1.0 Torr), blade rotation speed 5 rpm

During the polycondensation reaction in the second series, the liquid level was controlled so that the average residence time of each reactor was 60 minutes, and phenol by-produced in each reactor was distilled off.
The aromatic polycarbonate extracted from the fourth horizontal reactor 9b was in a molten state a biaxial extruder 11b equipped with a three-stage vent port (Kobe Steel Co., Ltd., screw diameter 0.046 m, L / D). = 36).
The extruder 11b was supplied with butyl p-toluenesulfonate and tris (2,4-di-t-butylphenyl) phosphite from the additive supply ports 12d and 12e, respectively. The supply amounts of these compounds were quantitatively supplied to the aromatic polycarbonate at concentrations of 5 ppm and 200 ppm, respectively.
The extrusion conditions of the extruder 11b were a discharge rate of 50 kg / h, a rotation speed of 150 rpm, and a maximum resin temperature of 285 ° C.

The strand-like aromatic polycarbonate discharged from the extruder 11b was pelletized by the strand cutter 14b via the strand bath 13b, removed from water by the centrifugal dehydrator 15b, and then introduced into the product silos 16c and 16d. In the product silos 16c and 16d, the following aromatic polycarbonates having good physical properties were stored.
Viscosity average molecular weight (Mv); 21,900
Terminal hydroxyl group concentration: 900 ppm
YI (yellowness) = 1.6

  Thus, in this example, two types of aromatic polycarbonates having different viscosity average molecular weights (Mv) and terminal hydroxyl group concentrations and different amounts and types of additives could be produced simultaneously.

Next, using the apparatus for producing an aromatic polycarbonate shown in FIG. 1, the pressure in the second series third vertical reactor 6f and the fourth horizontal reactor 9b was reduced to 0 after each continuous operation for about 200 hours. The production proceeded without changing the other conditions to 0.067 kPa (0.5 Torr).
As a result, an aromatic polycarbonate having the following physical properties and good hue was obtained by the second series of production apparatuses.
Viscosity average molecular weight (Mv); 22,300
Terminal hydroxyl group concentration: 300 ppm
YI (yellowness) = 1.6
In the second series, only the reaction pressure in the third vertical reactor 6f and the fourth horizontal reactor 9b was changed, and no switching loss of the molecular weight of the obtained aromatic polycarbonate occurred.
At this time, since the production conditions in the first series were not changed, no change in the properties of the aromatic polycarbonate was observed.

(Comparative Example 1)
Next, the example which manufactures an aromatic polycarbonate with the manufacturing apparatus which has only one series of polycondensation processes is demonstrated.
FIG. 2 is a diagram for explaining an apparatus for producing an aromatic polycarbonate having one polycondensation process sequence with respect to one original process sequence. The specifications of each device were the same as those in the original process and the first series in the aromatic polycarbonate production apparatus used in Example 1, and the same reference numerals were used.
In the apparatus for producing an aromatic polycarbonate shown in FIG. 2, except that the blade rotation speed of the fourth horizontal reactor 9a in the polycondensation step was changed to 10 rpm, and the DPC melt was not supplied from 1a-2. The polycondensation operation was carried out under the same conditions as the production conditions in the first series of Example 1, and the following aromatic polycarbonates having good physical properties were obtained.
Viscosity average molecular weight (Mv); 21,200
Terminal hydroxyl group concentration: 200 ppm
YI (yellowness) = 1.6

Next, after the continuous operation was continued for 200 hours, in order to produce an aromatic polycarbonate having a viscosity average molecular weight (Mv) of 15,000, the production conditions of the original preparation process and the polycondensation process were changed as follows.
The DPC melt prepared at 120 ° C. under a nitrogen gas atmosphere and the BPA powder weighed under the nitrogen gas atmosphere were supplied to the first raw material mixing tank 2a from the DPC supply port 1a-1 and the BPA supply port 1b, respectively. DPC was measured with a micro motion type flow meter and a loss-in-weight type weight feeder so that the supply rate was 88.7 kg / h, and BPA was a supply rate of 89.8 kg / h (DPC / BPA molar ratio 1.065). . The first raw material mixing tank 2a is set to 140 ° C. under an atmospheric pressure nitrogen atmosphere and includes an anchor type stirring blade 3a.

When the liquid level of the first raw material mixing tank 2a exceeds the same height as the highest position in the transfer pipe (that is, corresponding to the internal volume of 0.26 m ³ of the first raw material mixing tank 2a), the raw material mixture becomes the second. It is transferred to the raw material mixing tank 2b. The second raw material mixing tank 2b is set to 140 ° C. under an atmospheric pressure nitrogen atmosphere, has an internal volume of 0.4 m ³ , and includes an anchor type stirring blade 3b.
The total residence time of the raw material mixture required to pass through the first raw material mixing tank 2a and the second raw material mixing tank 2b was 160 minutes. The raw material mixture did not undergo transesterification, and the BPA reaction rate was 0%.

Next, the raw material mixture was continuously supplied to the first vertical reactor 6a via the raw material supply pump 4a. The first vertical reactor 6a includes a Max Blend blade 7a and has an internal volume of 0.1 m ³ .
Further, as the transesterification catalyst, an aqueous cesium carbonate solution (concentration: 0.011%) was supplied from a catalyst supply port 5a provided immediately before the first vertical reactor 6a of the transfer pipe at 292 ml / h (0. 50 × 10 ⁻⁶ mol).

The first vertical reactor 6a is maintained in a nitrogen atmosphere at a temperature of 220 ° C., a pressure of 13.33 kPa (100 Torr), a blade rotation speed of 160 rpm, and an average residence while distilling by-produced phenol from the by-product discharge pipe 8a. The liquid level was kept constant so that the time was 60 minutes.
The polymerization reaction liquid discharged from the first vertical reactor 6a continues to pass through the second vertical reactor 6b, the third vertical reactor 6c, and the lattice blade 10a having an internal volume of 0.1 m ³ equipped with the Max blend blade 7b. It was continuously supplied to the fourth horizontal reactor 9a having an internal volume of 0.15 m ³ provided.
The polycondensation reaction conditions in the second vertical reactor 6b to the fourth horizontal reactor 9a were set to the following conditions so as to become high temperature, high vacuum, and low stirring speed as the reaction progressed.

Second vertical reactor 6b; temperature 240 ° C., pressure 2.00 kPa (15 Torr), blade rotation speed 131 rpm
Third vertical reactor 6c; temperature 260 ° C., pressure 0.09 kPa (0.7 Torr), blade rotation speed 44 rpm
Fourth horizontal reactor 9a; temperature 265 ° C., pressure 0.09 kPa (0.7 Torr), blade rotation speed 5 rpm

During the polycondensation reaction, the liquid level was controlled so that the average residence time of each reactor was 60 minutes, and phenol by-produced in each reactor was distilled off.
The aromatic polycarbonate extracted from the fourth horizontal reactor 9a is a two-screw extruder 11a (manufactured by Kobe Steel, Ltd., screw diameter 0.046 m, L / D) provided with a three-stage vent port in a molten state. = 36).
The extruder 11a was supplied with butyl p-toluenesulfonate and tris (2,4-di-t-butylphenyl) phosphite from the additive supply ports 12a and 12b, respectively. The supply amounts of these compounds were quantitatively supplied to the aromatic polycarbonate at concentrations of 5 ppm and 50 ppm, respectively.
The extrusion conditions of the extruder 11a were a discharge rate of 50 kg / h, a rotation speed of 150 rpm, and a maximum resin temperature of 278 ° C.

The strand-like aromatic polycarbonate discharged from the extruder 11a was pelletized by the strand cutter 14a via the strand bath 13a, removed from water by the centrifugal dehydrator 15a, and then introduced into the product silos 16a and 16b. In the product silos 16a and 16b, aromatic polycarbonates having the following physical properties were continuously stored.
Viscosity average molecular weight (Mv); 15,100
Terminal hydroxyl group concentration: 880 ppm
YI (yellowness) = 1.9
These aromatic polycarbonates housed in the product silos 16a and 16b deteriorated in color. In addition, it took about 20 hours for the viscosity average molecular weight (Mv) and terminal hydroxyl group concentration of the aromatic polycarbonate to become stable in the production operation, and the aromatic polycarbonate produced during this time became a switching loss.

(Comparative Example 2)
Next, an example will be described in which the raw material and the catalyst are mixed in the polycondensation step, and then the aromatic polycarbonate is produced by a plurality of polycondensation steps.
FIG. 3 is a diagram showing an example of an apparatus for producing an aromatic polycarbonate having a primary process 1 series for preparing a mixture of a raw material and a catalyst and a polycondensation process 2 series. The specifications of each device are the same as those of the original process, the first series, and the second series in the aromatic polycarbonate production apparatus used in Example 1, and the same symbols are used.

In the apparatus for producing an aromatic polycarbonate shown in FIG. 3, in the raw material process, the DPC melt and BPA powder are supplied to the first raw material mixing tank 2a, and a cesium carbonate aqueous solution (concentration 0.011%) is used as a transesterification catalyst. ) Was continuously supplied at 408 ml / h from the catalyst supply port 5a.
Further, in the second series, an aqueous cesium carbonate solution (concentration 0.011%) as a transesterification catalyst is continuously supplied at 88 ml / h from the catalyst supply port 5b provided immediately before the first vertical reactor 6d of the transfer pipe. Supplied.
Other than the manufacturing conditions described above, the following two types of aromatic polycarbonates having different viscosity average molecular weights (Mv) and terminal hydroxyl group concentrations are the same as the manufacturing conditions in the aromatic polycarbonate manufacturing apparatus used in Example 1. Were simultaneously manufactured continuously.

First series viscosity average molecular weight (Mv); 13,700
Terminal hydroxyl group concentration: 1270ppm
YI (Yellowness) = 2.6
Second series viscosity average molecular weight (Mv); 20,100
Terminal hydroxyl group concentration: 1020 ppm
YI (yellowness) = 2.9

  From the above results, in the polycondensation based on the transesterification reaction between the aromatic dihydroxy compound and the carbonic acid diester, the raw material and the catalyst are mixed in the original process as in the production apparatus shown in FIG. When the aromatic polycarbonate is produced by the polycondensation step, it can be seen that the molecular weight of the aromatic polycarbonate does not reach the target and the color tone tends to deteriorate in both the first series and the second series.

(Example 2)
Next, an example will be described in which an aromatic polycarbonate is produced by a plurality of polycondensation steps by additionally adding a carbonic acid diester filtered through a filter after the original preparation step.
FIG. 4 is a diagram showing an example of an apparatus for producing an aromatic polycarbonate to which carbonic acid diester filtered through a filter is additionally added after the original preparation step. The specifications of each device are the same as those of the original process, the first series, and the second series in the aromatic polycarbonate production apparatus used in Example 1, and the same symbols are used.

As shown in FIG. 4, in the first series, the DPC melt prepared at 120 ° C. in a nitrogen gas atmosphere is passed through a SUS316L filter 1f having an absolute filtration accuracy of 0.5 μm, and then a transfer pipe for the raw material mixture The DPC supply port 1a-2 provided in the middle was supplied at a flow rate of 1.03 kg / h so that the (DPC / BPA) molar ratio of the entire raw material mixture was 1.065.
In addition, as the transesterification catalyst, an aqueous cesium carbonate solution (concentration 0.011%) was supplied from the catalyst supply port 5a provided at the top of the first vertical reactor 6a to 204 ml / h (0.35 × 10 5 per 1 mol of BPA). ^-6 mol) continuously. The other manufacturing conditions in the first series and the second series are the same as those in the first embodiment.
As a result, in the first series and the second series, aromatic polycarbonates having the same physical properties as in Example 1 and good hue were obtained.

1f ... filter, 2a ... first raw material mixing tank, 2b ... second raw material mixing tank, 3a, 3b ... anchor type stirring blade, 4a, 4b ... raw material supply pump, 5a, 5b ... catalyst supply port, 6a, 6d ... first 1 vertical reactor, 6b, 6e ... 2nd vertical reactor, 6c, 6f ... 3rd vertical reactor, 7a, 7b, 7c, 7d, 7e, 7f ... Max blend blade, 8a, 8b, 8c, 8d, 8e, 8f, 81, 82 ... by-product discharge pipe, 9a, 9b ... fourth horizontal reactor, 10a, 10b ... lattice blade, 11a, 11b ... extruder, 12a, 12b, 12c, 12d, 12e, 12f ... Additive supply port, 13a, 13b ... Strand bath, 14a, 14b ... Strand cutter, 15a, 15b ... Centrifugal dehydrator, 16a, 16b, 16c, 16d ... Product silo

Claims (5)

A process for continuously producing an aromatic polycarbonate by melt polycondensation by an ester exchange reaction between an aromatic dihydroxy compound and a carbonic acid diester,
A raw material preparation step for preparing a raw material molten mixture of an aromatic dihydroxy compound and / or a carbonic acid diester in the absence of a transesterification catalyst (hereinafter, sometimes abbreviated as “primary step”);
A polycondensation step in which the raw material melt mixture prepared in the original preparation step is polycondensed in the presence of a transesterification catalyst using a plurality of reactors. Having a condensation step,
A process for continuously producing an aromatic polycarbonate, wherein the transesterification catalyst is added during the transfer from the original preparation process to the polycondensation process of the plurality of series or in the initial stage of the polycondensation process.   The method for continuously producing an aromatic polycarbonate according to claim 1, wherein the transesterification catalyst is added after being filtered through a filter.   2. The aromatic polycarbonate according to claim 1, wherein any one or more selected from an aromatic dihydroxy compound, a carbonic acid diester, a terminal terminator, an additive, and a thermoplastic resin are added after the original preparation step. Continuous manufacturing method.   2. The method for continuously producing aromatic polycarbonates according to claim 1, wherein plural types of aromatic polycarbonates of the same type and / or different types are produced in the polycondensation step of a plurality of series.   2. The method according to claim 1, wherein any one or more selected from an aromatic dihydroxy compound, a carbonic acid diester, a terminal terminator, an additive, and a thermoplastic resin is added after filtering through a filter after the original preparation step. The continuous manufacturing method of the aromatic polycarbonate of description.

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