JPH0827265A - Production of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To produce an aromatic polycarbonate excellent in impact resistance, having high molecular weight and improved in hue and molecular weight distriburion. CONSTITUTION:This method for producing an aromatic polycarbonate is to supply a molten mixture of an aromatic diol compound and a diester of carbonic acid into a vertical agitation reactor 1, directly add an ester-interchange catalyst into the molten mixture without bringing the catalyst into contact with the gas phase in the vertical agitation reactor, carry out a polycondensation reaction and obtain a polycarbonate having 1,000-20,000 Mw, which is supplied to a horizontal polymerizer 5 having plural horizontally revolving shafts with mutually different revolution rate and multi-stage agitating blades fixed to each of the horizontally revolving shafts and scratch bars continuously connecting the agitation blades further carry out the polycondensation reaction and obtain the polycarbonate having 12,000-80,000 Mw.

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 a polycarbonate by a transesterification reaction. More specifically, an aromatic polycarbonate having improved heat resistance is produced from an aromatic diol compound and a carbonic acid diester by a melt polycondensation reaction. It is about the method.

[0002]

2. Description of the Related Art In recent years, aromatic polycarbonate has been used as a carbonated beverage bottle, an electronic substrate (CD substrate), a transfer sheet as an engineering plastic excellent in mechanical properties such as impact resistance, heat resistance and transparency. Belts, etc.
Widely used in many fields.

As a method for producing this aromatic polycarbonate, a so-called phosgene method in which an aromatic diol such as bisphenol and phosgene are reacted by an interfacial polycondensation method has been industrialized. However, this phosgene method
It has been pointed out that phosgene, which is toxic to the human body, must be used and that a large amount of by-produced sodium chloride is mixed into the produced polymer, causing problems such as corrosion when used in electronic devices.

Further, a method of obtaining an aromatic polycarbonate by transesterification of an aromatic diol compound and a carbonic acid diester has long been known as a so-called melting method or non-phosgene method. The non-phosgene method is said to have the advantages that the above-mentioned various problems of the phosgene method do not occur and that the aromatic polycarbonate can be produced at a lower cost. However, since the non-phosgene method is a bulk polymerization reaction method, the viscosity of the reaction mixture increases with an increase in the molecular weight of the aromatic polycarbonate, and by-products such as phenol can be efficiently removed from the reaction mixture in the post-polymerization step. There was a problem that it would be difficult.

In order to solve this problem, a manufacturing method using an apparatus having a special stirring type has been proposed. For example, JP-A-63-23926 discloses a method for producing a carbonate bond-containing polymer by transesterification from a divalent phenol and a carbonic acid diester in the presence or absence of an aromatic dicarboxylic acid ester, Disclosed is a method for producing a polycarbonate characterized in that a carbonate bond-containing prepolymer is continuously polycondensed in a molten state under reduced pressure by using a twin-screw vent type kneading extruder having blades combining a screw and a paddle. ing. This product has a drawback that the obtained polycarbonate has a poor hue.

Further, Japanese Patent Laid-Open No. 2-153925 discloses that
When melt-polycondensing an aromatic organic dihydroxy compound and a carbonic acid diester to produce a polycarbonate, the above-mentioned monomer mixture is melted and a vertical rotating shaft and a stirring blade attached to this vertical rotating shaft are provided. At least 1
The polycondensation reaction is carried out by supplying it to a horizontal reaction tank of 2 or more bases.
The first polycondensation reaction step for obtaining a polycarbonate having an intrinsic viscosity [η] of 0.05 to 0.4 dl / g measured in a methylene chloride solution at 0 ° C. and the polycarbonate obtained in the first polycondensation step. A horizontal rotation axis and mutually discontinuous stirring blades mounted substantially at right angles to the horizontal rotation axis, and the length of the horizontal rotation axis is L and the rotation diameter of the stirring blade is D Is supplied to at least one or more horizontal stirring polymerization tanks having L / D of 1 to 15 to carry out a polycondensation reaction to obtain a polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 dl / g. A method for producing a polycarbonate is described, which comprises a second polycondensation reaction step. In this polycarbonate production method, the second polycondensation reaction step requires a long time, and the hue of the obtained polycarbonate is poor.

Further, in JP-A-2-153926, in producing a polycarbonate by melt polycondensation of an aromatic organic dihydroxyl compound and a carbonic acid diester,
While melting the above monomer mixture, the polycondensation reaction is carried out by supplying to at least one or more thin film type evaporators for evaporating distillates such as phenol produced by the polycondensation reaction and partially unreacted monomers, The intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C is 0.05 to 0.4 dl /
a first polycondensation reaction step for obtaining a polycarbonate of g and a polycarbonate obtained in the first polycondensation step, and a horizontal rotating shaft and mutually discontinuous stirring blades mounted substantially at right angles to the horizontal rotating shaft. And L is the length of the horizontal rotating shaft and D is the rotating diameter of the stirring blade, and L / D is 1 to 15 and the weight is supplied to at least one horizontal stirring polymerization tank. A method for producing a polycarbonate is described, which comprises a second polycondensation reaction step of performing a condensation reaction to obtain a polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 dl / g. This method for producing polycarbonate has the drawbacks that the catalyst is lost due to the use of a thin film evaporator, the efficiency of the catalyst is poor, and the resulting polycarbonate has a poor hue and low impact resistance.

[0008]

The object of the present invention is to solve the above-mentioned problems of the prior art, to provide an aromatic polycarbonate having excellent impact resistance and an improved hue. To provide.

[0009]

The present invention provides a method for producing an aromatic polycarbonate by subjecting an aromatic diol compound and a carbonic acid diester to a melt polycondensation reaction in the presence of a transesterification catalyst, the first step; A molten mixture of a group diol compound and a carbonic acid diester is supplied into a vertical stirring reaction tank, and a transesterification catalyst is directly added to the above-mentioned molten mixture without passing through a gas phase portion in the vertical stirring reaction tank to perform polycondensation. Reacting,
A first step of obtaining an aromatic polycarbonate having a weight average molecular weight of 1,000 to 20,000, and a second step; the aromatic polycarbonate obtained in the first step,
A horizontal type having a plurality of horizontal rotating shafts, a multi-stage stirring blade attached to each of the horizontal rotating shafts, and a scraping rod continuously connecting the stirring blades, each horizontal rotating shaft having a different rotation speed. It is fed into the polymerization tank to carry out a polycondensation reaction, and the first
It has a higher molecular weight than the aromatic polycarbonate obtained in the step and has a weight average molecular weight of 12,000 to 80,000.
A second step of obtaining an aromatic polycarbonate having a value of 0, and a method for producing an aromatic polycarbonate, which comprises producing a polycarbonate through the second step.

[0010]

The prepolymer and the polymer are sufficiently agitated, the reaction rate is fast, the aromatic polycarbonate having a higher molecular weight, a narrow molecular weight distribution and less coloring can be produced.

[0011] DETAILED DESCRIPTION OF THE INVENTION Hereinafter, process for producing an aromatic polycarbonate according to the present invention will be described in detail. In the present invention, an aromatic diol compound and a carbonic acid diester are used when producing an aromatic polycarbonate. The aromatic diol compound used in the production of the present invention is a compound represented by the general formula [1].

[0012]

Embedded image

(In the formula, A is a single bond, a substituted or unsubstituted linear, branched or cyclic divalent hydrocarbon group having 1 to 10 carbon atoms, and -O-, -S-, -CO. -, -SO-, -S
It is selected from the group consisting of divalent groups represented by O ₂ —, X and Y are the same or different from each other and are selected from hydrogen or halogen or a hydrocarbon group having 1 to 6 carbon atoms. And p and q are integers of 0-2. )

Some representative examples are, for example, bis (4-hydroxydiphenyl) methaca, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl). propane,
2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5
-Dimethylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromo) propane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) cyclohexane, etc. Bisphenol; 4,4'-dihydroxybiphenyl-3,
Biphenols such as 3 ', 5,5'-tetramethyl-4,4'-biphenyl; bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide,
Bis (4-hydroxyphenyl) ether, bis (4-
Hydroxyphenyl) ketone and the like. Of these, 2,2-bis (4-hydroxyphenyl) propane is preferable.

Two or more kinds of these compounds may be used in combination (copolymer), and in the case of producing a branched aromatic polycarbonate, a small amount of polyhydric phenol having a valence of 3 or more is copolymerized. You can also Further, for the purpose of further improving the thermal stability and hydrolysis resistance of the aromatic polycarbonate produced, monovalent compounds such as pt-butylphenol and p-cumylphenol are used for the purpose of sealing the hydroxyl terminal. Phenols can also be used.

Typical examples of the carbonic acid diester used in the present invention include dimethyl carbonate, diphenyl carbonate, ditolyl carbonate, bis (4-chlorophenyl) carbonate and bis (2,4,6-trichlorophenyl) carbonate. . These carbonic acid diester compounds are generally used in excess with respect to 1 mol of the aromatic diol compound, and are used in an amount of 1.01 to 1.30 mol, preferably 1.02 to 1.20 mol. Is desirable.

In the present invention, it is preferable to use an alkali metal compound and / or an alkaline earth metal compound as the catalyst. Specific examples of such alkali metal compounds and alkaline earth metal compounds include organic hydrochloric acid, inorganic hydrochloric acid, acid compounds, hydroxides, hydrides or alcoholates of alkali metals and alkaline earth metals. .

More specifically, examples of the alkali metal compound 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 stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium phenyl borohydride, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate. , Dilithium hydrogen phosphate, disodium salt of bisphenol A,
Dipotassium salt, dilithium salt, sodium salt of phenol, potassium salt, lithium salt, cesium hydroxide, cesium carbonate, cesium hydrogen carbonate, cesium borohydride, cesium nitrate, inorganic cesium salts such as cesium sulfate, cesium acetate, stearin Organic acid cesium salts such as cesium acid and cesium benzoate, alcohol cesium salts such as cesium methylate and cesium ethylate, cesium phenolate, and phenolic cesium salts such as the cesium salt of bisphenol A.

Specific examples of the alkaline earth metal compound include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate and calcium carbonate. , Barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, strontium stearate and the like. These compounds may be used alone or in combination.

In the present invention, a basic compound can be used as the catalyst together with the above-mentioned alkali metal compound and / or alkaline earth metal compound. Examples of such a basic compound include a nitrogen-containing basic compound and a phosphonium hydroxide compound which are easily decomposable or volatile at high temperature and rarely remain in the final aromatic polycarbonate and do not adversely affect physical properties such as hue. The following compounds are specifically mentioned.

The nitrogen-containing basic compound is tetramethyi.
Lumonium hydroxide (Me _Four NOH), Tetra
Ethyl ammonium hydroxide (Et_Four NOH), TE
Trabutylammonium hydroxide (Bu_Four NO
H), trimethylpentylammonium hydroxide
(Φ-CH₂ (Me)₃ Alkyl such as NOH), ant
Amyl having an aryl, araryl group, etc.
Xides, trimethylamine, triethylamine, dime
Tertiary amines such as tylbenzylamine and triphenylamine
Mins, R₂ NH (where R is an alkyl group such as methyl or ethyl)
For example, aryl groups such as kill, phenyl, and toluyl.
Secondary amines, RHN₂ (Where R is the above
The same as the above), a primary amine represented by
Imidazo such as imidazole and 2-phenylimidazole
Or ammonia, tetramethylammonium
Mbboro hydride (Me_Four NBH_Four ), Tetrabutyl
Ammonium borohydride (Bu_Four NBH_Four ), Te
Trabutylammonium tetraphenylborate (Bu
_Four NBPh_Four ), Tetramethylammonium tetrafe
Nilvolade (Me_Four NBPh_Four ) And other basic salts
You can

Examples of the phosphonium hydroxide compound include tetraethylphosphonium hydroxide, tetrabutylphosphonium hydroxide, tetraphenylphosphonium hydroxide, methyltriphenylphosphonium hydroxide, allyltriphenylphosphonium hydroxide, butyltriphenylphosphonium hydroxide, Examples thereof include amyl triphenyl phosphonium hydroxide, heptyl triphenyl phosphonium hydroxide, hexyl triphenyl phosphonium hydroxide, benzyl triphenyl phosphonium hydroxide, and cinnamyl triphenyl phosphonium hydroxide.

Of these, tetraalkylammonium hydroxide, tetrabutylphosphonium hydroxide and tetraphenylphosphonium hydroxide are preferably used. When a basic compound is used as the catalyst, the basic compound is usually 1 × 10 ⁻⁶ to 1 × 10 ⁻¹ mol, preferably 1 × 10 ⁻⁵ to 1 × with respect to 1 mol of the aromatic diol compound. Used in an amount of 10 ^-2 mol. next,
The method for producing the aromatic polycarbonate according to the present invention will be described.

First step : In the atmosphere of an inert gas such as nitrogen gas, for example, a molten mixture of 2,2-bis (4-hydroxyphenyl) propane as an aromatic diol compound and diphenyl carbonate as a carbonic acid diester is introduced as a raw material. It is supplied into the vertical stirring reaction tank 1 through the pipe 2.

This vertical stirring reaction tank 1 comprises at least one or more turbine blades, paddle blades, anchor blades, helical ribbon blades, double helical ribbon blades, MaxBlend having a shape along the inner surfaces of the bottom wall and side wall of the tank. Tsubasa ("Chemical Engineering Handbook, 5th revised edition" page 911; published by Maruzen) and ("Assessment 13 of polymer manufacturing process" Reactive Processing PART2 "", page 246 published by Japan Society of Polymer Science)
And the like.

Among these, it is preferable to use a vertical stirring reaction tank equipped with Maxblend blades having a shape along the inner surfaces of the bottom wall and side wall of the tank, which has stirring performance in a wide viscosity range. In the present invention, the vertical stirring reaction tank 1 is used.
At least one is used. The vertical stirring reaction tank is controlled to the temperature and pressure conditions described below, and the alkali metal compound and / or the alkaline earth metal compound and / or the basic compound of the catalyst are vertically passed through the catalyst introducing pipe 3 inserted in the above-mentioned molten mixture. It is added directly to the molten mixture without passing through the gas phase portion in the mold stirring reaction tank 1, and the reaction is proceeded while removing by-products from the by-product discharge pipe 4.

The reaction temperature in the first step is 100 ° C to 300 ° C.
C., more preferably in the range of 180.degree. C. to 280.degree. C., and the reaction pressure is in the range of atmospheric pressure to 1 mmHg. In the first step, an aromatic polycarbonate having a weight average molecular weight of 1,000 to 20,000 is obtained.

Second Step The aromatic polycarbonate obtained in the first step is provided with a plurality of horizontal rotary shafts 6a, 6b and multistage stirring blades 7, 7, ... Attached to each horizontal rotary shaft. Then, it is supplied into the horizontal polymerization reaction tank 5 in which the rotation speeds of the horizontal rotation shafts 6a, 6b ... Are different, and phenol and by-products produced under the temperature and pressure conditions suitable for the third step, which will be described later, The polycondensation reaction is further promoted while removing some unreacted raw material monomers to the outside of the system through the vent conduit 8.

The stirring blades have a shape in which a disc is cut out, a horizontal shape, a rectangular shape, a horseshoe shape, or a combination thereof, and are installed in multiple stages for each rotary shaft. As shown in FIGS. 1 and 2, this horizontal biaxial polymerization tank 5 has two parallel rotating shafts 6a and 7b and a stirring blade having a shape in which a multistage disc attached to each of the parallel rotating shafts is cut out. 7 and a scraping rod 7a connecting the stirring blades. Moreover, the number of blades mounted on one of the two horizontal rotary shafts is two or more, and the number of blades mounted on the other shaft is an integral multiple of the one, and the shaft rotation of the two horizontal shafts is performed. The ratio is the reciprocal of the number of blades of the stirring blade, and the apparatus has a scraping rod that connects the outer periphery of the multi-stage stirring blade.

In the above horizontal type biaxial polymerization tank, a large gas-liquid interface area can be obtained by the unevenness of the liquid free surface and the thin film formed by the liquid entrained in the scraping rod, and the reaction time can be shortened. Since the residence time can be shortened as compared with the conventional device, deterioration of the hue of the aromatic polycarbonate can be suppressed.
Also, in this horizontal biaxial polymerization tank, the relative peripheral speed difference is caused by the difference in rotation speed between the two horizontal rotary shafts, so that the mixing characteristics are excellent, the condensation reaction time can be shortened, and the residence time of the polymer in the tank 5 can be shortened. Since it can be shorter than the conventional method, deterioration of the hue of the obtained aromatic polycarbonate can be suppressed.

Further, in the horizontal type biaxial polymerization tank, the reaction mixture may adhere to the rotary shaft and the stirring blade by the action of the stirring blade having a notched disk shape and the scraping rod connecting the outer circumference of the stirring blade. Since the amount is small, the colored deposit is unlikely to be mixed into the aromatic polycarbonate. The temperature of the second step is in the range of 200 ° C to 330 ° C, and the reaction pressure is 2
It is 0 mmHg or less. The polycarbonate obtained in the second step has a weight average molecular weight of 12,000 to 80,000.
Is.

In an aromatic polycarbonate having a wide molecular weight, the presence of a low molecular weight component causes a decrease in the mechanical strength of the obtained molded product, and the high molecular weight component is
Since there are many coloring components derived from a relatively long residence time, it becomes a factor of deteriorating the hue of the molded body. Therefore, in order to obtain an aromatic polycarbonate having excellent mechanical strength and an improved hue, it is necessary to produce a high molecular weight aromatic polycarbonate having a narrow molecular weight distribution in a short time.

In the present invention, the heat resistance stabilizer, ultraviolet absorber, release agent, antistatic agent, slip agent, antiblocking agent, lubricant, antifogging agent, etc. which are usually used in the aromatic polycarbonate obtained as described above, Additives such as natural oils, synthetic oils, waxes, organic fillers and inorganic fillers may be added. Such additives can be added to the aromatic polycarbonate in a molten state, or the aromatic polycarbonate once pelletized can be remelted and added. Remelting is preferably performed in an inert gas atmosphere.

The steps of the present invention can be carried out by a continuous method, a batch method, a combination of continuous and batch methods, and any method may be used. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0035]

EXAMPLES The aromatic polycarbonate obtained according to the present invention was analyzed by the following measuring method. (1) Molecular weight It is a GPC (Tosoh HLC-8020) polycarbonate conversion molecular weight in 35 degreeC using a chloroform solvent.

(2) Hue A 10% methylene chloride solution is used to measure a diameter of 25 mm and a height of 55 mm.
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.) and the YI value, which is an index of yellowness, is calculated by the following relational expression. Was calculated.

[0037]

[Equation 1] The larger the YI value, the more the coloring.

(3) Mixing of foreign matter A sheet having a length of 50 mm, a width of 50 mm, and a thickness of 5 mm was press-molded, and the mixing of foreign matter was visually observed. 5 or less was set as a small amount, and 20 or more was set as a large amount.

(4) Izod impact strength (with notch) 280 using an injection molding machine [CS183MMX Minimax manufactured by Custom Scientific Co.]
Length at 31.5 mm, width at 6.2 ° C, length at 3.2 mm
Izod impact tester [Custto
Mini Scientific-138, manufactured by m Scientific
TI type], notched Izod impact strength at 23 ° C. (notch tip R = 0.25 mm, depth = 1.
2 mm) was measured.

Example 1 16.50 mol (3.767 kg) of bisphenol A and 17.7 diphenyl carbonate under a nitrogen gas atmosphere.
A molten mixture of 4 mol (3.800 kg) was equipped with Maxblend blades having a shape along the bottom wall and the inner surface of the side wall of a vertical stirring reaction tank through a raw material introduction pipe, and was controlled at 180 ° C in a 20-liter vertical vessel. 2% prepared by dissolving 0.5 g of cesium carbonate as a catalyst in 25 ml of distilled water.
80 μl of an aqueous cesium carbonate solution (3.0 × 10 ⁻⁷ mol per 1 mol of bisphenol A) and 304 μl of a 15% tetrabutylphosphonium hydroxide aqueous solution (1.0 × 10 ⁻⁵ mol per 1 mol of bisphenol A) were used as raw material monomers. Through the catalyst introducing pipe inserted into the molten mixture, it was directly added to the molten mixture without passing through the gas phase part in the vertical stirring reaction tank, and the stirring and molten state was maintained for 30 minutes.

Next, after raising the temperature of the reaction tank to 210 ° C.,
Gradually reduce the pressure to 150 mmHg and change the state to 3
Hold for 0 minutes to distill the phenol. Then 24
After raising the temperature to 0 ° C, gradually reduce the pressure to 15 mmHg,
The state was maintained for 1 hour. Further, the pressure was lowered to 1 mmHg at 240 ° C., and the state was maintained for 1 hour. The time required for the reaction in this vertical stirring reaction tank was 4 hours in total. Next, this aromatic polycarbonate was extracted from the lower part of the vertical stirring reaction tank by a gap pump. This first
The weight average molecular weight of the aromatic polycarbonate obtained in the step was 11,000.

Next, 3.5 kg of the aromatic polycarbonate obtained in the first step was kept at 240 ° C. to obtain a geometrical capacity of 7.7.
L-type horizontal biaxial polymerization tank ("Vivolac (trade name)" manufactured by Sumitomo Heavy Industries, Ltd .; two horizontal rotary shafts and a multi-stage disc-shaped agitator attached to each horizontal rotary shaft) A horizontal biaxial polymerization tank having blades and a scraping rod in which the stirring blades are continuously connected and having an axial rotation ratio of two horizontal rotary shafts of 2) is introduced, and the temperature is immediately raised to 280 ° C. The pressure was reduced to 0.8 mmHg, and the horizontal biaxial polymerization tank had a rotation speed of 40 rpm for the high-speed horizontal rotation shaft and 20 rpm for the low-speed horizontal rotation shaft.

The time required for the reaction in this horizontal biaxial polymerization tank was 0.5 hours in total. The polymerization average molecular weight of the aromatic polycarbonate obtained in this second step was 26,40.
It was 0. Other test results are shown in Table 1.

Example 2 16.50 mol (3.767 kg) of bisphenol A and 17.7 of diphenyl carbonate under a nitrogen gas atmosphere.
In a 20 liter vertical stirring reaction tank, which was equipped with a Maxblend blade having a shape along the inner surfaces of the bottom wall and side wall of the tank through a raw material introduction pipe, and a molten mixture with 4 mol (3.800 kg). Cesium carbonate as a catalyst 0.
80 μl of a 2% cesium carbonate aqueous solution in which 5 g was dissolved in 25 ml of distilled water (for 1 mol of bisphenol A, 3.0 ×
10 ⁻⁷ mol) and 304 μl of a 15% tetrabutylphosphonium hydroxide aqueous solution (1.0 × 10 ⁻⁵ mol per 1 mol of bisphenol A) are melted, and in a vertical stirring reaction tank through a catalyst introduction tube inserted into the mixture. Was directly added to the above-mentioned raw material monomer molten mixture without passing through the gas phase part of, and the stirring and molten state was maintained for 30 minutes.

Next, after raising the temperature to 210 ° C., the pressure is gradually increased to 1
The pressure was lowered to 50 mmHg, and the state was maintained for 30 minutes to distill phenol. Then, after raising the temperature to 240 ° C.,
The pressure was gradually lowered to 15 mmHg and the state was maintained for 1 hour. The time required for the reaction in this vertical stirring reaction tank was 3 hours in total. Next, this aromatic polycarbonate was extracted from the lower part of the vertical stirring reaction tank by a gap pump. The polymerization average molecular weight of the aromatic polycarbonate obtained in this prepolymerization step was 6,200.

Next, 3.5 kg of the aromatic polycarbonate obtained in the first step was kept at 240 ° C. in a horizontal biaxial polymerization tank having a geometrical capacity of 7.7 liters (“Vivolac; 2 pieces by Sumitomo Heavy Industries, Ltd.”). (A horizontal biaxial polymerization tank having a horizontal rotary shaft and a multi-stage disc-shaped agitating blade attached to each horizontal rotary shaft and having an axial rotation ratio of two horizontal rotary shafts of 2) And immediately reduced the pressure to 0.8 mmHg while raising the temperature to 280 ° C. At this time, the rotation speed of the horizontal rotary shaft on the high speed side of the horizontal biaxial polymerization tank was 40 rpm, and the rotation speed of the horizontal rotary shaft on the low speed side was 40 rpm. , 20 rpm.

The time required for the reaction in this horizontal biaxial polymerization tank was 1.5 hours in total. The polymerization average molecular weight of the aromatic polycarbonate obtained in the second step was 24,800. Other test results are shown in Table 1.

Comparative Example 1 In the second step of Example 1, a discontinuous stirring blade without a scraping rod was used, and the axial rotation ratio of two horizontal rotary shafts was 1,
An aromatic polycarbonate was obtained by carrying out the polymerization under the same conditions as in Example 1 except that a horizontal biaxial polymerization tank having a geometrical capacity of about 6 liters was used and the rotation speed of the two horizontal rotary shafts was 40 rpm. The above test was conducted on the obtained aromatic polycarbonate. The results are shown in Table 1.

Comparative Example 2 In the second step of Example 1, a discontinuous stirring blade without a scraping rod was used, and the axial rotation ratio of two horizontal rotary shafts was 1,
A horizontal biaxial polymerization tank with a geometric capacity of about 6 liters was used, and the rotation speed of two horizontal rotary shafts was 40 rpm.
Polymerization was carried out under the same conditions as in Example 1 except that the time required for the reaction in the step was extended to 2 hours to obtain an aromatic polycarbonate. The above-mentioned test was conducted on the obtained aromatic polycarbonate. The results are shown in Table 1.

COMPARATIVE EXAMPLE 3 In the second step of Example 2, having a discontinuous stirring blade without a scraping rod, the axial rotation ratio of two horizontal rotary shafts was 1, and
A horizontal biaxial polymerization tank with a geometric capacity of about 6 liters was used, and the rotation speed of two horizontal rotary shafts was 40 rpm.
Polymerization was performed under the same conditions as in Example 2 except that the time required for the reaction in the process was extended to 3 hours to obtain an aromatic polycarbonate. The above-mentioned test was conducted on the obtained aromatic polycarbonate. The results are shown in Table 1.

Comparative Example 4 In the first step of Example 1, the catalyst was added to the monomer melt mixture through the gas phase portion in the vertical stirring reaction tank, and the time required for the reaction in the second step was added. Was polymerized under the same conditions as in Example 1 except that the total time was 1.5 hours to obtain an aromatic polycarbonate. The above-mentioned test was conducted on the obtained aromatic polycarbonate. The results are shown in Table 1.
Shown in

[0052]

[Table 1]

[0053]

EFFECTS OF THE INVENTION According to the present invention, an aromatic polycarbonate having excellent impact resistance, improved hue and less foreign matter can be produced.

[Brief description of drawings]

FIG. 1 is a schematic view of a manufacturing apparatus according to the present invention.

FIG. 2 is a schematic cross-sectional view of a horizontal biaxial polymerization tank.

[Explanation of symbols]

 1 Vertical stirring reaction tank 2 Raw material introduction pipe 3 Catalyst introduction pipe 4 By-product discharge pipe 5 Horizontal biaxial polymerization tank 6a High-speed horizontal rotary shaft 6b Low-speed horizontal rotary shaft 7 Stirring blade 7a Scraping rod 8 Vent conduit

Claims (2)

[Claims] 1. A method for producing an aromatic polycarbonate by subjecting an aromatic diol compound and a carbonic acid diester to a melt polycondensation reaction in the presence of a transesterification catalyst, the first step comprising: mixing the aromatic diol compound with a carbonic acid diester. The molten mixture is supplied into the vertical stirring reaction tank, the transesterification catalyst is directly added to the molten mixture without passing through the gas phase portion in the vertical stirring reaction tank to carry out the polycondensation reaction,
A first step of obtaining an aromatic polycarbonate having a weight average molecular weight of 1,000 to 20,000, and a second step; the aromatic polycarbonate obtained in the first step,
A horizontal type having a plurality of horizontal rotating shafts, a multi-stage stirring blade attached to each of the horizontal rotating shafts, and a scraping rod continuously connecting the stirring blades, each horizontal rotating shaft having a different rotation speed. It is fed into the polymerization tank to carry out a polycondensation reaction, and the first
It has a higher molecular weight than the aromatic polycarbonate obtained in the step and has a weight average molecular weight of 12,000 to 80,000.
A second step of obtaining an aromatic polycarbonate having a value of 0, and a method for producing an aromatic polycarbonate, which comprises producing a polycarbonate. 2. The vertical stirring reaction tank of the first step is provided with a stirring blade on a rotating shaft provided at the center of the reaction tank, and a part of the stirring blade is formed along the inner surface of the tank wall. The method for producing an aromatic polycarbonate according to claim 1, wherein the aromatic polycarbonate has a Maxblend blade close to the inner surface of the formed tank wall.