JP2000007778A - Preparation of aromatic-aliphatic copolymer polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin having an excellent impact resistance, an excellent heat resistance, a high Abbe number, a low photoelasticity constant and an excellent color tone by polycondensing the mixture of an aromatic dihydroxy compound, an aliphatic dihydroxy compound and a diester carbonate continuously using a horizontal reaction vessel having specific mixing blades and a horizontal mixing polymerization vessel. SOLUTION: An aromatic dihydroxy compound of formula I, an aliphatic dihydroxy compound of formula II and a diester carbonate are used. A polymer having a weight average molecular weight of 30,000-60,000 is obtained by polycondensing a melt of the monomer mixture in at least one horizontal mixing polymerization vessel having a vertical rotation axis with mixing blades and then a polycarbonate having a weight average molecular weight of not less than 70,000 is obtained by carrying out the polycondensation further in at least one horizontal polymerization vessel having a horizontal rotation axis with mixing blades which are mutually discontinuous and have L/D of 1-15. In the formulas, X is formula III or IV; R1 and R2 are each hydrogen, a 1-10C alkyl group or a halogen; m and n are each 0-4; and R3 and R4 may bond each other to form a ring; R5 to R8 are each hydrogen or a monovalent 1-10C alkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing an aromatic-aliphatic polycarbonate having excellent impact resistance, low photoelastic constant, high refractive index and inverse dispersion value, and excellent transparency and heat resistance. More specifically, an aromatic-aliphatic copolymer obtained by a transesterification reaction between an aromatic dihydroxy compound represented by the above formula (1), an aliphatic dihydroxy compound represented by the above formula (2), and a carbonic acid diester is used. The present invention relates to a method for producing a polymerized polycarbonate.

[0002]

2. Description of the Related Art Polycarbonate is bisphenol A.
It is manufactured by a method known as an interfacial polymerization method from an aromatic dihydroxy compound and phosgene, or a method of transesterifying an aromatic dihydroxy compound and a carbonic acid diester such as diphenyl carbonate in a molten state. Because of its excellent mechanical properties and excellent heat resistance and transparency, it is used as an optical material for various lenses, prisms, optical disk substrates, and the like. However, in the polycarbonate using only bisphenol A as the aromatic dihydroxy compound, the photoelastic constant is large and the melt fluidity is relatively poor, so that the birefringence of the molded product becomes large, and the refractive index is as high as 1.58. However, since the Abbe number is as low as 30, there is a drawback that it does not have sufficient performance to be widely used for applications such as optical recording materials and optical lenses. The present inventors have previously proposed an aromatic-aliphatic copolymerized polycarbonate resin (Japanese Patent Application No. 8-276260) for the purpose of solving such a drawback of bisphenol A-polycarbonate. This aromatic-aliphatic copolymerized polycarbonate resin has excellent impact resistance and heat resistance, and furthermore has a small photoelastic constant and a high Abbe number, so that it can be widely used as an optical material.
Such aromatic-aliphatic copolymerized polycarbonate,
It is difficult to produce by the ordinary phosgene method, and a transesterification method in which an aromatic dihydroxy compound and an aliphatic dihydroxy compound, and a carbonic acid diester such as diphenyl carbonate are polycondensed by a transesterification reaction in a molten state is preferably used. .

In the transesterification reaction, the reaction temperature is raised from about 150 ° C. to about 330
C. and gradually lower the pressure of the reaction system from atmospheric pressure to about 0.1 mmHg, thereby efficiently proceeding the transesterification reaction to obtain a polycarbonate having a high molecular weight. However, as the reaction proceeds and the molecular weight increases, the melt viscosity of the reaction mixture becomes extremely high, and it becomes difficult to efficiently distill off by-products such as phenol from the reaction mixture. The problem has been pointed out.

In the aromatic-aliphatic copolymerized polycarbonate of the present invention, when a polycondensation reaction is carried out using a tank reactor, the polymerization time required to reach a predetermined molecular weight is reached because the transesterification rate is low. Since the viscosity is long and the melt viscosity greatly depends on the shear rate, it is not possible to increase the evaporation surface area per unit processing amount, such that heat generated by shearing increases unless the stirring speed is reduced significantly with increasing the molecular weight. Therefore, the residence time of the reaction mixture in the tank reactor needs to be extremely long. Therefore, the reaction mixture has a long thermal history, and the resulting product has a problem that the coloring of the product is very severe.

[0005]

SUMMARY OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above, and provides excellent impact resistance, heat resistance, high Abbe number and low photoelastic constant. It is an object of the present invention to provide a method for producing an aromatic-aliphatic polycarbonate resin having excellent color tone.

[0006]

Means for Solving the Problems Aromatic substances according to the present invention
A method for producing an aliphatic copolymerized polycarbonate is to polycondensate an aromatic dihydroxy compound represented by the above formula (1), an aliphatic dihydroxy compound represented by the above formula (2), and a carbonic acid diester under heating and melting. When producing the aromatic-aliphatic copolymerized polycarbonate by melting, the above monomer mixture is melted, and at least one or more tank-type reaction vessels equipped with a vertical rotation axis and a stirring blade attached to the vertical rotation axis And a polycondensation reaction is performed to obtain a polycarbonate having a weight average molecular weight of 30,000 to 60,000. The polycarbonate obtained in the first polycondensation step is horizontally rotated. With a shaft and mutually discontinuous stirring blades attached at substantially right angles thereto, and the length of the horizontal rotating shaft is L and the rotation diameter of the stirring blade is D A horizontal stirring polymerization tank having a / D of 1 to 15 or a stirring blade having no horizontal rotation axis and having a lattice-shaped stirring blade connected along a virtual horizontal rotation axis; When the length of the horizontal rotating shaft is L, and the rotating diameter of the stirring blade is D, L / D is supplied to at least one or more horizontal stirring polymerization tanks having 1 to 15 to perform a polycondensation reaction, And a second double condensation reaction step for obtaining a polycarbonate having a weight average molecular weight of 70,000 or more. According to the present invention, excellent impact resistance,
An aromatic-aliphatic polycarbonate having heat resistance, high Abbe number, low photoelastic constant, and excellent color tone can be produced.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing an aromatic-aliphatic polycarbonate according to the present invention will be specifically described.

The polycarbonate according to the present invention comprises a structural unit derived from an aromatic dihydroxy compound represented by the above formula (1) and a structural unit derived from an aliphatic dihydroxy compound represented by the above formula (2). And a structural unit derived from carbonic acid diester.

As the aromatic dihydroxy compound, bis (4-hydroxyphenyl) methane, 1,1-bis (4
-Hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, bis (4-hydroxy Phenyl) phenylmethane, 2,2-bis (4-hydroxy-
3-methylphenyl) propane, 1,1-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2
-Bis (4-hydroxy-3-bromophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethylphenyl ether, 4,4'-dihydroxyphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, , 4'-dihydroxy-3,3-dimethyldiphenylsulfoxide, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxy-3,
3'-dimethyldiphenyl sulfone or the like is used.

Of these, 2,2-bis (4-
Hydroxyphenyl) propane, bisphenol A, or 1,1-bis (4-hydroxyphenyl) cyclohexane is preferred.

As the aliphatic dihydroxy compound, 3,
9-bis (2-hydroxyethyl-2,4,8,10-
Tetraoxaspiro (5.5) undecane, 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,
4,8,10-tetraoxaspiro (5.5) undecane, 3,9-bis (2-hydroxy-1,1-diethylethyl) -2,4,8,10-tetraoxaspiro (5.5) Undecane, 3,9-bis (2-hydroxy-1,1-dipropylethyl) -2,4,8,10-tetraoxaspiro (5.5) undecane and the like are used. Preferably, 3,9-bis (2-hydroxy-1,
1-dimethylethyl) -2,4,8,10-tetraoxaspiro (5.5) undecane is used.

The polycarbonate resin according to the present invention comprises:
It comprises a structural unit derived from an aromatic dihydroxy compound represented by the above formula (1) and a structural unit derived from an aliphatic dihydroxy compound represented by the above formula (2),
A polycarbonate comprising a random, block, or alternating copolymer or a structural unit derived from an aromatic dihydroxy compound represented by the above formula (1) and an aliphatic dihydroxy compound represented by the above formula (2) Excellent heat resistance, and hue, because it contains a polycarbonate blend consisting of structural units
Shows a more balanced refractive index and dispersion properties,
It has the characteristic that the birefringence is low.

In the present invention, the molar ratio (I) of a structural unit derived from an aromatic dihydroxy compound (hereinafter, referred to as I) to a structural unit derived from an aliphatic dihydroxy compound (hereinafter, referred to as II). / II) is 9
It is preferably 0/10 to 10/90, and more preferably 80/20 to 20/80. That is, if the molar ratio (I / II) of the structural units derived from the aromatic dihydroxy compound (1) and the aliphatic dihydroxy compound (2) in the polycarbonate is lower than 10/90, the heat resistance becomes poor, and If the ratio is higher than / 10, the photoelastic constant, the water absorption and the like will increase, and the balance between the refractive index and the Abbe number will deteriorate, which is not preferable as an optical material.

In the present invention, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. are used as the carbonic acid diester. . Among these, diphenyl carbonate is particularly preferred. Diphenyl carbonate is used in an amount of 0.97 to 0.9 mol based on a total of 1 mol of the aromatic dihydroxy compound and the aliphatic dihydroxy compound.
It is preferably used in an amount of 1.2 mol, particularly preferably 0.99 to 1.10 mol.

The weight average molecular weight of the polycarbonate resin used in the present invention is preferably 30,000 to 200,000, more preferably 50,000 to 1
20,000.

In the method for producing a polycarbonate according to the present invention, a basic compound is used as a catalyst. Examples of such a basic compound include an alkali metal and / or alkaline earth compound, a nitrogen-containing compound, and the like.

Such compounds include organic acids such as alkali metals and alkaline earth compounds, inorganic salts, oxides, hydroxides, hydrides or alkoxides, quaternary ammonium hydroxides and salts thereof, amines and the like. Are preferably used, and these compounds can be used alone or in combination.

Such alkali metal compounds include:
Specifically, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium hydrogen carbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate,
Lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate , Dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenylphosphate, disodium salt of bisphenol A, 2 potassium salt, 2 cesium salt, 2 lithium salt, phenol sodium salt, potassium salt, cesium salt, lithium Salts and the like are used.

Further, as the alkaline earth metal compound,
Specifically, magnesium hydroxide, calcium hydroxide,
Strontium hydroxide, barium hydroxide, magnesium bicarbonate, calcium bicarbonate, strontium bicarbonate, barium bicarbonate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, magnesium stearate, calcium stearate, calcium benzoate, phenyl phosphate Magnesium or the like is used.

Examples of the nitrogen-containing compound include alkyl, aryl, tetraalkylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide. Ammonium hydroxides having an araryl group and the like, tertiary amines such as triethylamine, dimethylbenzylamine and triphenylamine, secondary amines such as diethylamine and dibutylamine, primary amines such as propylamine and butylamine,
Imidazoles such as 2-methylimidazole and 2-phenylimidazole, or basic salts such as ammonia, tetramethylammonium borohydride, tetrabutylammonium tetraphenylborate, and tetraphenylammonium tetraphenylborate are used.

These catalysts are used in an amount of 10 ^-9 to 10 ^-3 mol, preferably 10 ^-7 to 1 ^-1 mol, per mol of the aromatic dihydroxy compound and the aliphatic dihydroxy compound in total.
Used in an amount of 0 ^-5 mol.

Next, a method for producing an aromatic-aliphatic copolymer polycarbonate according to the present invention will be described with reference to the drawings.
FIG. 1 is an example of a process chart for carrying out a method for producing an aromatic-aliphatic copolymer polycarbonate according to the present invention.

[First Polycondensation Reaction Step] First, as a raw material monomer, for example, bisphenol A which is an aromatic dihydroxy compound and 3,9-bis which is an aliphatic dihydroxy compound are placed in a tank-type stirring tank 1 under a nitrogen atmosphere. (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-
Tetraoxaspiro (5.5) undecane and diphenyl carbonate as a carbonic acid diester are introduced in a molten state through the raw material introduction pipes 2, 3, and 4, respectively, and these raw material monomers are sufficiently stirred and mixed. Is supplied to a tank-type reaction vessel 6 having a vertical rotation shaft and a stirring blade attached to the vertical rotation shaft via a raw material transfer conduit 5. The tank-type reaction tank 6 includes at least one or more turbine blades, paddle blades, anchor blades,
Helical ribbon wings or wings obtained by improving these wings are provided. In the present invention, at least one or more such tank-type reaction tanks are used.

In the tank-type reaction tank 6 controlled at the transesterification reaction starting temperature, a conduit 8 for transferring a prepared raw material while adding a small amount of a basic catalyst through a catalyst introduction pipe 7.
To the tank type reaction tank 9 controlled at a temperature and pressure suitable for conducting the first polycondensation reaction, and the reaction mixture is further reacted to obtain a polycarbonate.

The reaction temperature in the first polycondensation reaction is as follows:
Usually 100 ° C to 300 ° C, preferably 150 to 280 ° C
And the pressure can be reduced from normal pressure to 0.1 mmHg. In this case, the lower limit pressure of the reduced pressure condition is 400 to 0.1 mmHg, preferably 200 to 0.
It can be set in the range of 1 mmHg.

In the first polycondensation reaction step, a polycarbonate having a weight average molecular weight of 30,000 to 60,000, more preferably 40,000 to 50,000 is obtained.

The phenol vapor by-produced in this reaction and a part of the unreacted monomer vapor are passed through the conduit 10.
, And the phenol and a part of the unreacted monomer are cooled and liquefied. The liquefied phenol and a part of the unreacted monomer are accumulated in the phenol reservoir via the conduit 13. Uncondensed phenol is
It is collected by a cold trap via a vent conduit 12.

[Second Polycondensation Reaction Step] Next, the polycarbonate obtained in the first polycondensation reaction step is connected to a horizontal rotating shaft and a cross-connecting member mounted substantially at right angles thereto via a prepolymer transfer conduit 14. And a discontinuous stirring blade,
And the length of the horizontal rotation axis is L, and the rotation diameter of the stirring blade is D.
A horizontal stirring polymerization tank having an L / D of 1 to 15,
Alternatively, there is provided a stirring blade having no horizontal rotation axis and having a lattice-shaped stirring blade connected along a virtual horizontal rotation axis, and the length of the virtual horizontal rotation axis is set to L, Is supplied to a horizontal stirred polymerization tank 15 having an L / D of 1 to 15 when the rotation diameter of the phenol is D, and under the temperature and pressure conditions suitable for performing the second polycondensation reaction, A polycondensation reaction is carried out by removing part of the unreacted monomers to the outside of the system via a vent conduit 16.

This horizontal stirring polymerization tank 15 can be used in one or two
At least two or more horizontal stirring shafts, and one or more stirring blades such as a disk type, a wheel type, a paddle type, a rod type, a window frame type, etc. It may be a horizontal high-viscosity liquid treatment device that is installed with more than one stage, and the surface of the reaction solution is renewed by lifting or spreading the reaction solution by the stirring blade, or it may not have a horizontal stirring shaft, and may have a lattice shape. A horizontal high-viscosity liquid processing apparatus that renews the surface of the reaction solution by agitating or pushing up the reaction solution with a stirring blade having at least two or more stirring blades connected along a virtual horizontal stirring axis. good. In the present invention, at least one or more such horizontal stirring polymerization tanks are used.

The reaction temperature in the second polycondensation reaction is as follows:
Usually 180-300 ° C, preferably 220-28
0 ° C.

In the second polycondensation reaction step, a polycarbonate having a weight average molecular weight of 70,000 or more, preferably 80,000 or more is obtained.

Next, in order to maintain thermal stability and hydrolysis stability, it is preferable to remove or deactivate the catalyst, and to add an alkali metal or alkaline earth by adding a known acidic substance. A method of deactivating a transesterification catalyst such as a metal is suitably performed. Specific examples of these substances include aromatic sulfonic acid such as p-toluenesulfonic acid, aromatic sulfonic acid esters such as butyl p-toluenesulfonic acid, hexyl p-toluenesulfonic acid, stearic acid chloride, butyric acid. Organic halides such as chloride, benzoyl chloride and p-toluenesulfonic acid chloride, alkyl sulfates such as dimethyl sulfate, organic halides such as benzyl chloride, and inorganic acids such as boric acid and phosphoric acid are preferably used.

Further, in the present invention, the above heat stabilizer,
In addition to hydrolysis stabilizers, antioxidants, pigments, dyes, reinforcing agents and fillers, ultraviolet absorbers, lubricants, release agents, crystal nucleating agents, plasticizers, flow improvers, antistatic agents, etc. Can be added.

These additives may be introduced directly into the extruder via the resin transfer conduit 17 and added in the molten state, or may be added after the molten resin is cooled and solidified and pelletized. Each component can be mixed with the polycarbonate resin by a conventionally known method. For example, a method in which each component is dispersed and mixed by a high-speed mixer represented by a turnbull mixer, a Henschel mixer, a ribbon blender, or a super mixer, and then melt-kneaded by an extruder, a Banbury mixer, a roll, or the like is appropriately selected.

[0035]

By using the method for producing an aromatic-aliphatic copolymer polycarbonate according to the present invention, it is possible to obtain excellent impact resistance, heat resistance, etc., as well as refractive index, dispersion balance and photoelastic constant. Can be produced without deteriorating the color tone, so that it can be suitably used for plastic optical materials such as various lenses, prisms and optical disk substrates.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples.

[0037]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 2,2-bis (4-hydroxyphenyl) propane 77
17 g (33.8 mol), 3,3'-bis (2-hydroxy-1,1-dimethylethyl) -2,4,8,10-
9498 g (31.2 mol) of tetraoxaspiro (5.5) undecane (hereinafter referred to as spiroglycol), 14861 g (69.37 mol) of diphenyl carbonate,
And sodium bicarbonate 0.1 as a transesterification catalyst.
016 g was charged into a 50-liter stirred tank equipped with a stirrer and a distilling apparatus, and after purging with nitrogen, heated to 200 ° C. and completely dissolved, followed by stirring for 30 minutes. Thereafter, the degree of pressure reduction was adjusted to 150 mmHg, and at the same time, the temperature was raised to 260 ° C., and the transesterification reaction was carried out while distilling off by-product phenol. When the distillation of phenol was substantially completed, the degree of vacuum was further increased, and the mixture was stirred for 1 hour under the condition of 1 mmHg or less, and then returned to atmospheric pressure with nitrogen. The time required for the reaction was 4 hours. Next, the reactant was added at 4 kg / cm.
Withdrawing in a strand form from the lower part of the reaction tank under the pressure of ² ,
The pellet was cut with a pelletizer. The weight average molecular weight of this prepolymer was 60,000. Next, the prepolymer was extruded into a twin-screw lattice blade polymerization machine (L / D = 2.8, no horizontal stirring shaft, blade number: 6, internal volume: 24 liters) controlled at 260 ° C. and 0.3 mmHg by an extruder. The polymerization was carried out at a feed residence time of 1 hour at 0.2 kg / h. The weight average molecular weight of the obtained polymer is 80,000.
Met. Table 1 shows the physical properties of the polymer.

Example 2 In Example 1, a two-shaft horizontal stirring polymerization tank (L) having a horizontal stirring shaft and a glasses-type stirring blade vertically attached thereto was used.
/D=2.6, internal volume 24 liters) except that a polymer was obtained, and the physical properties of the obtained polymer were examined. Table 1 shows the results.

Example 3 A polymer was obtained in exactly the same manner as in Example 1, except that the prepolymer was supplied from the extruder at a feed rate of 3.6 kg / h to the twin-screw horizontal polymerization stirring tank. The residence time in the horizontal polymerization stirring tank at this time was 2 hours. Table 1 shows the results.

Comparative Example 1 In Example 1, polymerization was carried out using only a vertical reaction tank having a double helical ribbon stirring blade without using a horizontal stirring polymerization stirring tank. That is, when the distillation of phenol is substantially completed, the degree of vacuum is further increased, and the mixture is stirred for 1 hour under the condition of 1 mmHg or less, and then the polymerization is advanced while the stirring rotation speed is gradually lowered. .2mmH
g, the stirring torque is 20 kgw at a stirring rotation speed of 3 rpm.
When the pressure reached m, the stirring was stopped and the pressure was returned to atmospheric pressure with nitrogen.
The time required for the reaction was 8 hours. Next, the reaction product was drawn out in a strand form from the lower part of the reaction tank under a pressure of 4 kg / cm ² and cut into pellets by a pelletizer. The weight average molecular weight of this polymer was 85,000.
Table 1 shows the physical properties of the obtained polymer.

The physical properties in Table 1 are measured by the following methods.

(1) Molecular weight: GPC (Shodex G
It was measured as a molecular weight in terms of styrene (weight average molecular weight: Mw) using PC system 11). Chloroform was used as a developing solvent. (2) Resin YI: The obtained resin was press-molded into a disc having a diameter of 40 mm and a thickness of 3 mm, and a color difference meter (Tokyo Denshoku TC-1)
800MK2) to measure the YI value (yellowness).

[0044]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a process diagram of a method for producing an aromatic-aliphatic copolymerized polycarbonate.

[Explanation of symbols]

 1: tank type stirring tank 2: raw material introduction pipe 3: raw material introduction pipe 4: raw material introduction pipe 5: raw material transfer pipe 6: tank type reaction tank 7: catalyst introduction pipe 8: raw material transfer pipe 9: tank type reaction tank 10: Conduit 11: Condenser 12: Vent Conduit 13: Conduit 14: Prepolymer Transfer Conduit 15: Horizontal Stirred Polymerization Tank 16: Vent Conduit 17: Resin Transfer Conduit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Takashi Tsunoda 22nd Wadai, Tsukuba-shi, Ibaraki F-term in Mitsubishi Gas Chemical Co., Ltd. BG08X BG17X BG20X BG24X BH02 DB07 DB11 DB13 HA01 HC04A HC05A JA091 JA121 JA261 JA301 JB131 JB171 JC031 JC091 JC261 JC731 JF021 JF031 JF041 JF051 JF131 JF141 JF151 JF161 KD01 LA07

Claims (2)

[Claims] An aromatic-fatty compound obtained by polycondensing an aromatic dihydroxy compound represented by the following formula (1), an aliphatic dihydroxy compound represented by the following formula (2), and a carbonic acid diester under heating and melting. When producing the aromatic polycarbonate, the above monomer mixture is melted and supplied to at least one or more tank-type reaction tanks having a vertical rotation shaft and a stirring blade attached to the vertical rotation shaft. A condensation reaction is carried out and the weight average molecular weight is 30,000 to 60,000.
A first polycondensation reaction step for obtaining polycarbonate which is 0, the polycarbonate obtained in the above first polycondensation step, having a horizontal rotating shaft and mutually discontinuous stirring blades attached substantially at right angles thereto. And the length of the horizontal rotation axis is L
And when the rotating diameter of the stirring blade is D, L / D is 1 to
15 or a horizontal stirring polymerization tank having no horizontal rotation axis, having a stirring blade formed by connecting lattice-shaped stirring blades along a virtual horizontal rotation axis, and having a virtual horizontal rotation axis. When the length is L and the rotating diameter of the stirring blade is D, L / D
Is supplied to at least one or more horizontal stirring polymerization tanks having a weight average molecular weight of 70,
And a second double condensation reaction step for obtaining a polycarbonate having a molecular weight of 000 or more. Embedded image (In the above formula (1), X is Wherein R ₃ and R ₄ are a hydrogen atom or a carbon atom
To 10 alkyl groups or phenyl groups, and R ₃ and R ₄ may combine to form a ring. R ₁ and R ₂ is a hydrogen atom or an alkyl group or a halogen having 1 to 10 carbon atoms, R ₁
And R ₂ may be the same or different. Also, m and n
Represents the number of substituents and is an integer of 0 to 4. ) (In the above formula (2), R ₅ , R ₆ , R ₇ , and R ₈ are a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms.) 2. The method according to claim 1, wherein the aliphatic dihydroxy compound is 3,9-bis (2-hydroxy-1,1-dimethylethyl) -2,
The method for producing an aromatic-aliphatic copolymer polycarbonate according to claim 1, which is 4,8,10-tetraoxaspiro (5.5) undecane.