JP2000319379A - Method for producing aromatic polycarbonate resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aromatic polycarbonate resin excellent in hue. SOLUTION: This method for producing an aromatic polycarbonate resin features comprising using a vertical mixing vessel equipped with a mixing blade having 0.4<2r/D<1.0 in the case where a diameter of a reaction vessel is D (m) and a length of the mixing blade is r (m) as a reactor used in the range of <=10,000 viscosity-average molecular weight, and using a reactor having <=400 (mol/Hr.m2) F/A in the case where a heat transfer area of a heating part installed at the inside and/or the outside of the vertical mixing vessel is A (m2) and a supplying amount of an aromatic dihydroxy compound is F (mol/Hr), and operating (mixing) in N×2r>0.5 (m/sec) in the case where a number of rotation for mixing is N (1/sec).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aromatic polycarbonate resin, and more particularly, to a method for producing an aromatic polycarbonate resin having excellent hue.

[0002]

2. Description of the Related Art Polycarbonate (aromatic 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 (interface method), or a method in which an aromatic dihydroxy compound such as bisphenol and a carbonic acid diester such as diphenyl carbonate are melted. A method of transesterification (melting method) 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 of producing a polycarbonate by transesterification reaction is said to deteriorate the quality of the obtained polycarbonate, especially the hue, because the polymerization is carried out for a long time under severe conditions compared to the interface method, that is, at a high temperature and a high degree of vacuum. Had a problem.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polycarbonate resin having an excellent hue by using a transesterification method which does not have environmental problems and is economical.

[0005]

That is, the present invention comprises the following technology.

[0006] 1. In a method in which a plurality of reactors are installed in series and an aromatic dihydroxy compound and a carbonic acid diester are reacted in the presence / absence of a catalyst to continuously produce an aromatic polycarbonate resin, the viscosity average molecular weight is 1
For the reactor used in the area of 000 or less, the tank diameter is D
(M), when the blade length is r (m), 0.4 <2r / D
Using a vertical stirring tank equipped with a stirring blade of <1.0, and
When the heat transfer area of the heat transfer unit provided inside and / or outside the vertical stirring tank is A (m ² ) and the supply amount of the aromatic dihydroxy compound is F (mol / Hr), F / A When a reactor having a flow rate of 400 (mol / Hr · m ² ) or less is used and the number of rotations for stirring is N (1 / second), N ×
A method for producing an aromatic polycarbonate resin, wherein the operation is performed at 2r> 0.5 (m / sec).

[0007] 2. 2. The method according to the above item 1, wherein the stirring blade is a paddle blade.

[0008] 3. 3. The method according to the above item 1 or 2, wherein the carbonic acid diester is diphenyl carbonate.

4. 4. The method according to any one of the above items 1 to 3, wherein the catalyst is an alkali metal compound or an alkaline earth metal compound and a nitrogen-containing basic compound.

[0010] In the present specification, the inside diameter of the reaction tank means the diameter inside the reaction tank. In addition, in this specification, it may be called "tank diameter." The blade length refers to the length of one or more stirring blades attached to the stirring shaft with respect to the stirring shaft as viewed from the center of rotation of the shaft due to stirring to the peripheral direction of rotation (the length of the stirring shaft). (Measured from the axis), and the blade width described later indicates the width of the stirring blade in a direction orthogonal to the blade length. In the specification of the present application, the above-mentioned 2r / D and the blade width H described later are applied to each of one or more stirring blades attached to a stirring shaft in a reaction tank. R
Uses the maximum of them. When the blade length of each of the stirring blades changes to, for example, a trapezoidal shape, the maximum value is used. The same applies to the case where the blade width changes for each of the stirring blades.

As a result of studying a method for producing a polycarbonate having an excellent hue by a transesterification reaction, the initial reaction of the transesterification was carried out by a specific method.
It was found that a polycarbonate having an excellent hue was obtained.

The effect of the present invention depends on the degree of polymerization to be applied, and the viscosity-average molecular weight is at most 10,000, preferably at most 9,000, more preferably at most 8,000 in the relatively early region of the transesterification reaction. A remarkable effect can be obtained by applying the method described above. Although the cause is not clear, the decomposition of the monohydroxy compound generated by the transesterification reaction is involved in the deterioration of the hue of the obtained polycarbonate, and therefore, the generation of the monohydroxy compound is active in the early region of the transesterification reaction. It is presumed to have a great effect.

Further, the type of the apparatus used in the initial region of the transesterification reaction having a viscosity average molecular weight of 10,000 or less greatly affects the hue of the obtained polycarbonate.

In the present invention, the inner diameter of the reaction vessel is D
(M), when the stirring blade length is r (m), 0.4 <2r
A vertical stirring tank equipped with a large paddle blade having a ratio of /D<1.0 is preferably used. The ratio of the stirring blade length to the inner diameter of the reactor is 0.4
Below, the hue of the obtained polymer is undesirably deteriorated. In addition, it is necessary to avoid contact of the stirring blade with the inner wall of the reaction tank, and therefore, the ratio of the stirring blade length to the inner diameter of the reaction tank needs to be less than 1.0, preferably 0.9 or less. Must be 0.8 or less.

The ratio (H / r) between the blade width and the blade length of the large paddle blade used in the present invention is not particularly limited, but is preferably in the range of 1 to 5. Also, a notch may be provided at the upper part of the paddle wing, and may be formed in a grid shape.
Furthermore, each stirring blade is divided into a plurality in the stirring axis direction,
Those having different phases can also be preferably used.

The paddle blade used in the present invention is basically a flat plate, but may have a bent tip or a trapezoidal shape having different blade lengths in the blade width direction.

In the present invention, the stirring rotation speed is also an important factor, and using the large paddle blade as described above,
Assuming that the stirring rotation speed is N (1 / second), N × 2r> 0.
It is necessary to stir at 5 (m / s). If the tip speed (N × 2r) of the blade is lower than this value, the hue of the obtained polymer is undesirably deteriorated.

In the present invention, it is important to provide a heating mechanism having an appropriate heat transfer area in the initial region of the transesterification reaction with respect to the supply amount of the aromatic dihydroxy compound used as a raw material. That is, the heat transfer area of the heat transfer unit installed inside and / or outside the vertical stirring tank used in the initial region of the transesterification reaction is A
(M ² ), the supply amount of the aromatic dihydroxy compound is F (m
ol / Hr), the F / A is 400 (mol / Hr).
rm ² ) or less, it is possible to obtain a polycarbonate having an excellent hue.

In the present invention, the viscosity average molecular weight is 1
When the initial region of the transesterification reaction of 000 or less is carried out by using two or more reactors, the heat transfer area A is the sum of these.

According to the study by the present inventors, it is not possible to stably produce polycarbonate having excellent hue simply by defining the relationship between the effective volume of the initial polymerization tank and the heat transfer area. It was found that a polycarbonate having an excellent hue could be stably obtained by melt polymerization only when the total heat transfer area of the heat transfer portion existing in the initial region of the transesterification reaction was defined.

In the present invention, the total heat transfer area of the heat transfer portion existing in the initial region of the transesterification reaction is defined as a value between the preheating of the raw material melt and the reactor having a viscosity average molecular weight exceeding 10,000. Means the sum of the heat transfer areas of the equipment having all the heating mechanisms. That is, the “heat transfer section” is a heat transfer section in the rigid stirring tank, a heat transfer section in a supply pipe to the rigid stirring tank, and an external circulation attached to the rigid stirring tank for external circulation heating. It is a general term for the heat transfer part of the heating device.

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

Specific examples of such aromatic dihydroxy compounds include bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 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 are listed, and 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.

Specific 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, dicyclohexyl carbonate and the like are used, and diphenyl carbonate is particularly preferable.

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

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

Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate,
Potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium nitrate, potassium nitrate, lithium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, sodium sulfite, potassium sulfite, lithium sulfite, sodium cyanate, potassium cyanate , Lithium cyanate, sodium thiocyanate,
Potassium thiocyanate, lithium thiocyanate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, potassium borohydride, lithium borohydride, sodium phenylated borate, sodium benzoate, potassium benzoate, benzoate Examples thereof include lithium acid, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt, dipotassium salt, dilithium salt of bisphenol A, sodium salt, potassium salt, and lithium salt of phenol.

The alkali metal compound as a catalyst is preferably used in such a ratio that the alkali metal element in the catalyst is 1 × 10 ^{−8 to} 5 × 10 ⁻⁵ equivalent per 1 mole of the aromatic diol compound. A more desirable ratio is 5 × for the same standard.
The ratio is 10 ^-7 to 1 × 10 ^-5 equivalent. If the amount is outside the above range, the properties of the obtained polycarbonate are adversely affected, and the transesterification reaction does not sufficiently proceed to obtain a high-molecular-weight polycarbonate, which is not preferable.

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

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

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

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

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

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

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

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

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

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

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

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

By using these cocatalysts at a specific ratio, the terminal block reaction and the polycondensation reaction rate are not impaired, the branching reaction which is easily generated during the polycondensation reaction, 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.

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

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

The co-catalyst should be present in a proportion such that the metal element of Group 14 of the periodic table in the co-catalyst is not more than 50 mol (atoms) per 1 mol (atom) of the alkali metal element in the polycondensation reaction catalyst. preferable. If the co-catalyst is used in a proportion of more than 50 moles (atoms) of the same metal element, the rate of the polycondensation reaction is undesirably reduced.

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

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

The reactor used in the present invention for carrying out the initial region of the transesterification reaction separates unreacted carbonic acid diester and by-product monohydroxy compound and refluxes unreacted carbonic acid diester in the reaction system. A vertical stirring tank equipped with a rectification tower for performing the above is widely used. Further, the material of the reactor needs to have corrosion resistance to the monohydroxy compound produced as a by-product, and a material having a low iron content such as nickel or stainless steel is preferably used in a portion in contact with the reaction solution.

The reactant that has completed the initial region of the transesterification reaction is transferred to a reactor for performing the latter transesterification reaction, and the transesterification reaction is continued to a predetermined degree of polymerization. As the latter reactor used for this purpose, a vertical or horizontal stirring tank is used, but a horizontal reactor in which the liquid depth is kept low is preferable. In addition, a rectification column is generally not provided because the reaction pressure is often a high degree of vacuum and there is no unreacted carbonic diester enough to affect the molar balance of the raw materials. Although the material constituting the late reactor is not so strictly required as that of the early reactor, a material containing much iron should also be avoided, and is preferably made of stainless steel or the like.

The molar ratio of the carbonic acid diester to the aromatic dihydroxy compound varies depending on the capacity of the rectification column, the conversion of the monomers in the initial reactor, and the amount of OH end groups of the polycarbonate to be obtained. 5 preferably 0.95 to 1.1, more preferably 1.0 to 1.05
Is used.

The operating conditions of the initial reactor are 180 to 250
C., preferably at a temperature of 200-250.degree.
Torr pressure is used. When the initial region of the transesterification reaction is carried out using a plurality of reactors, it is preferable that the operating temperature and the degree of vacuum are sequentially strengthened as the transesterification reaction proceeds.

The operating conditions for the late reactor are 250-300.
° C, preferably 260-290 ° C and 10-0.1
Torr, and preferably a pressure of 5 to 0.5 Torr is used. When the latter stage reaction is carried out using a plurality of reactors, it is preferable that the operating temperature and the degree of vacuum are sequentially strengthened in a later stirred tank. In this way, in the latter stage reactor, the polymerization is carried out to a viscosity average molecular weight exceeding 10,000, and preferably 15,000 or more, depending on the purpose.

The reactant produced in the latter polymerization tank is quantitatively extracted using a gear pump or the like, and after adding additives as necessary, it is made into a product. And filtering the reaction. As the filter used for this purpose, a known filter such as a candle type, a pleated type or a disk type is preferably used, and the openings thereof have a viscosity average molecular weight of 20,000 of the product.
In the following cases, those having a size of 40 μm or less, and those having a size of 40 μm or less are 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. The equipment used to carry out such an operation is not particularly limited, but for example, a twin-screw ruder is preferable, and when a stabilizer is dissolved or dispersed in a solvent, a vented twin-screw ruder is particularly preferably used. You.

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, release agents of fatty acid esters such as glycerin monostearate and stearate of pentaerythritol, 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, an aromatic polycarbonate resin is produced by installing two or more reactors in series to react an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. In the method, a reactor having a specific stirrer in the initial region of the transesterification reaction is used under specific conditions, the obtained prepolymer is supplied to a subsequent reactor, and the polymer is further polymerized, so that the color of the polymer is changed. A method for producing a polycarbonate resin that 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 Examples and Comparative Examples, the intrinsic viscosity of a 0.7 g / dl methylene chloride solution was measured using an Ubbelohde viscometer, and the viscosity average molecular weight was determined by the following equation. [Η] = 1.23 × 10 ⁻⁴ × M ^{0.83 As} the measured value of the polymer hue, polycarbonate pellets (short diameter × long diameter × length (mm) = 2.5 × 3.3 ×
3.0) L, a, and b values of ND-100 manufactured by Nippon Denshoku Industries
Among the results measured by the reflection method using 1DP, the b value was used as a measure of yellowness.

Example 1 Diphenyl carbonate was charged into a melting tank equipped with a stirrer at a ratio of 1.01 mol to 1 mol of 2,2-bis (4-hydroxyphenyl) propane, and nitrogen was added thereto. After the replacement, the mixture was heated and melted at 150 ° C., and the molten mixture was transferred to a raw material storage tank whose temperature was controlled at 150 ° C.
After the raw material storage tank, continuous operation was performed.

The details of the continuous operation will be described below.
From the raw material storage tank, a 2,2-bis (4-
100 mol / hr of hydroxyphenyl) propane and 101 mol / hr of diphenyl carbonate were continuously fed to the first vertical reaction tank, and 2,2-bis (4-hydroxyphenyl) propane was fed. For 1 mole,
1 × 10 ⁻⁶ equivalent of sodium phenoxide and 1 × 10 ⁻⁴
An equivalent amount of tetramethylammonium hydroxide was continuously added to the reactor in a separate line from the line.

The vertical reactor of the first stage is provided with two large paddle blades that satisfy 2r / D = 0.6 when the tank diameter is D (m) and the blade length is r (m). Phenol produced and vaporized by transesterification and partially vaporized raw material (2,
2-bis (4-hydroxyphenyl) propane and diphenyl carbonate) are continuously rectified in a rectification column attached to the reaction tank, and then transesterification is performed while only phenol is distilled out of the reaction system. It proceeded continuously.

The first vertical reaction tank was set at 220 ° C.
13,333 Pa (100 mmHg), stirring speed is N
In this case, the operation was performed at a stirring rotation speed at which N × 2r = 0.9.

The prepolymer having a viscosity average molecular weight of 1,500 generated in the first vertical reaction tank was continuously withdrawn from the bottom of the tank using a gear pump, and was continuously transferred to the second vertical reaction tank. Feeded.

The specific values of D, r, and N are as follows. D = 0.7 (m) r = 0.21 (m) N = 2.1 (1 / sec)

The vertical reactor in the second stage has a reactor diameter of D
(M), when the blade length is r (m), 2r / D = 0.6
5 with a stirring blade and a rectification tower.
In the case where N × 2r = 0.55, the stirring rotation speed becomes
The internal temperature is 250 ° C and the internal pressure is 2,000 Pa (15 mmH
g).

As a result, a prepolymer having a viscosity average molecular weight of 6,000 was obtained from the outlet side of the second-stage reaction vessel, and the prepolymer was continuously fed to the final-stage polycondensation reactor using a gear pump. Feeded.

The specific values of D, r, and N are as follows. D = 0.65 (m) r = 0.21 (m) N = 1.3 (1 / sec)

The sum of the heat transfer areas inside the first and second reactors (the area of contact between the jacket and the internal heat transfer coil) is A
(M ²⁾ and then, when the supply amount of the starting material 2,2-bis (4-hydroxyphenyl) propane was F (mol / hr), F / A = 125 (mol / hr · m 2) met Was.

As the polycondensation reactor in the last stage, a horizontal single-shaft reactor was used. The internal temperature was 270 ° C., and the internal pressure was 133 Pa (1 mmH).
g), the polycondensation reaction was allowed to proceed continuously while all the phenol and the like produced were distilled out of the reaction system.

The polymer obtained in the polycondensation reactor at the final stage was continuously extracted using a gear pump, extruded from a die, and then pelletized by a pelletizer. When the viscosity average molecular weight of the obtained pellet was measured, the viscosity average molecular weight was 15,500, and the b value of the hue was −0.1.
It was 2.

[Comparative Example 1] N × in the first stage reactor
2r = 0.15, N × 2r in the second stage reactor =
The same procedure as in Example 1 was carried out except that the stirring rotation speed was changed to 0.1, and the viscosity average molecular weight of the polymer pellets obtained in the final stage polycondensation reactor was measured. 500 and the hue is 0.5.
Met. The viscosity average molecular weight generated in the first-stage vertical reaction tank was 1500, and the viscosity average molecular weight generated in the second-stage reaction tank was 6000.

Comparative Example 2 N × in the First Stage Reactor
2r = 0.15, 2r / D = 0.25, N × 2r in the second stage reactor = 0.1, 2r / D = 0.25, and the stirring blades were changed to stirring speed and rotation speed. When carried out in the same manner as in Example 1, the viscosity average molecular weight of the polymer pellets obtained in the final stage polycondensation reactor was measured, and the viscosity average molecular weight was 15,500. there were. The viscosity average molecular weight generated in the first-stage vertical reaction tank was 1500, and the viscosity average molecular weight generated in the second-stage reaction tank was 6000.

Comparative Example 3 N × in the First Stage Reactor
2r = 0.15, 2r / D = 0.25, N × 2r in the second stage reactor = 0.1, 2r / D = 0.25, and the number of stirring blades and the number of rotations were changed. By removing the heat transfer coil inside the second stage reactor, F / A =
Except having changed to 500, it carried out similarly to Example 1 and measured the viscosity average molecular weight of the polymer pellet obtained by the polycondensation reactor of the last stage.
The hue was 5,500, and the b value was 1.1. The viscosity average molecular weight generated in the first vertical reaction tank is 1
500, the viscosity average molecular weight generated in the second stage reaction vessel is 6
000.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Sawaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Co., Ltd. Inside the Iwakuni Research Center (72) Inventor Katsushi Sasaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Shares F-term in the Iwakuni Research Center (reference) 4J029 AA10 AB05 AB07 AC01 AD10 BB04A BB05A BB05B BB10A BB12A BB13A BB13B BF14A BG05X BG08X BG24X BH02 DB07 DB11 DB13 HC04A HC05A HC05B JA091JA1JJAJA1JA01JJ1JJA1J1JA1 JF371 KB02 KB05 KD01 KD07 KE02 KE05 LA02 LA08 LA10

Claims (4)

[Claims] 1. A method for continuously producing an aromatic polycarbonate resin by installing a plurality of reactors in series and reacting an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst. With a molecular weight of 10,
For the reactor used in the area below 000, the tank diameter is D
(M), when the blade length is r (m), 0.4 <2r / D
A vertical stirring tank equipped with a stirring device having a stirring blade of <1.0 was used, and the heat transfer area of the heat transfer section installed inside and / or outside the vertical stirring tank was A (m ² ) When the supply amount of the aromatic dihydroxy compound is F (mol / Hr), use a reactor having an F / A of 400 (mol / Hr · m ² ) or less, and stir the stirring device. When the number of rotations is N (1 / second), N × 2r> 0.5 (m /
Seconds), a method for producing an aromatic polycarbonate resin. 2. The method according to claim 1, wherein the stirring blade is a paddle blade. 3. The method according to claim 1, wherein the carbonic acid diester is diphenyl carbonate. 4. The method according to claim 1, wherein the catalyst is an alkali metal compound or an alkaline earth metal compound and a nitrogen-containing basic compound.