JP2674813B2 - Method for producing polycarbonate - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing a polycarbonate, and more particularly to a method for producing a polycarbonate by a transesterification reaction between an aromatic organic dihydroxyl compound and a carbonic acid diester.

Technical Background of the Invention and Problems Thereof Polycarbonate is widely used because it has excellent mechanical properties such as impact resistance, and also has excellent heat resistance and transparency. One of the methods for producing such a polycarbonate is a method in which an aromatic organic dihydroxy compound such as bisphenol and a carbonic acid diester such as diphenyl carbonate are subjected to a transesterification reaction (polycondensation reaction) in a molten state. For example, Belgian Patent No. 532543 (19
(54) The specification discloses a method of obtaining a polycarbonate by subjecting bisphenol A and diphenyl carbonate to a transesterification reaction in a molten state in the presence of a small amount of a transesterification catalyst to remove by-produced phenol to obtain a polycarbonate. ing. The transesterification reaction performed in the molten state is generally a bulk polymerization reaction, and the by-produced phenol is gradually mixed under stirring and mixing with the minimum temperature required to start the transesterification reaction from about 150 ° C to about 350 ° C. It is distilled off from the reaction mixture by gradually lowering the reaction pressure from atmospheric pressure to about 0.1 mmHg.

However, the viscosity of the reaction mixture becomes extremely high as the completion of the above-mentioned reaction approaches (depending on the reaction conditions, about 10,000 to 100,000 poise or more), distillate such as by-product phenol is efficiently removed from the reaction mixture. There was a problem that it was difficult to remove well.

In order to solve this problem, conventionally, the transesterification reaction involves a pre-polycondensation step of synthesizing a low-molecular weight prepolymer under normal stirring conditions in a state where the viscosity of the reaction mixture is relatively low, and a high viscosity of the reaction mixture. In this state, it is divided into a post-polycondensation step in which a high-molecular weight polymer is synthesized using a special stirring type. The transesterification reaction in the pre-polycondensation step to synthesize a low molecular weight prepolymer is
Generally, a tank-type reactor is used, and the reaction is performed in a batch system or a continuous system. The transesterification in the polycondensation stage after the synthesis of a high molecular weight polymer can be performed in a batch type using a tank reactor with a stirring device with a special shape of stirring blade, or a centrifugal thin film evaporator, vented extruder, etc. Is performed in a continuous manner using

However, none of the above methods has been effective in distilling off by-products such as phenol from the reaction mixture efficiently and satisfactorily.

By the way, when a tank reactor is used as the polycondensation reactor in the final stage of the transesterification reaction, it is not possible to increase the evaporation surface area per unit treatment amount of the reaction mixture. It is necessary to increase the residence time. Therefore, the reaction mixture has a long heat history, and thus has a problem that the obtained product has a high degree of coloring.

When a centrifugal thin-film evaporator is used as the polycondensation reactor in the final stage of the transesterification reaction, the reaction mixture can have a large evaporation surface area per unit throughput, so the centrifugal thin-film evaporation of the reaction mixture can be achieved. The residence time in the machine can be shortened. However, since a part of the produced polymer adheres to the rotating shaft, the blades, the internal bearings and the like and undergoes a long heat history, there is a problem that the blackened decomposition product is mixed into the polymer.

Further, when a single-screw vented extruder is used as the polycondensation reactor in the final stage of the transesterification reaction, an undesired colored product is obtained because part of the generated polymer adheres to the screw groove. There is a problem.

When a self-cleaning type twin-screw vented extruder is used as a polycondensation reactor in the final stage of the transesterification reaction, the polymer hardly adheres to the screw portion, so that a colored product is not generated. Absent. However, this twin-screw vent type extruder has a small hold-up due to the structure of the device, and the cost of the device per unit effective volume is extremely high, so that there is a limit to the scale-up. Therefore, it is necessary to minimize the residence time of the reaction mixture as much as possible, and the reaction temperature and the degree of vacuum must be set to more severe conditions as compared with the pre-polycondensation reaction step. There is a problem of coloring and deterioration.

Object of the Invention The present invention is to solve the problems associated with the prior art as described above, has excellent mechanical properties,
Moreover, it is an object of the present invention to provide a method for producing a polycarbonate capable of obtaining a polycarbonate having an improved color tone.

SUMMARY OF THE INVENTION The method for producing a polycarbonate according to the present invention, when producing a polycarbonate by melt polycondensation of an aromatic organic dihydroxyl compound and a carbonic acid diester, under the melting of the monomer mixture, a vertical rotation axis, The polycondensation reaction is carried out by supplying to at least one or more tank-type reaction tanks equipped with a stirring blade attached to a vertical rotating shaft, and the intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C is 0.05 to A first polycondensation reaction step for obtaining a polycarbonate of 0.4 dl / g; and a polycarbonate obtained in the first polycondensation step,
This polycarbonate is formed into a thin film and is supplied to at least one or more thin film type evaporators for evaporating distillates such as phenol and some unreacted monomers produced by the reaction to carry out a polycondensation reaction to obtain the above-mentioned intrinsic viscosity [ a second polycondensation reaction step for obtaining a polycarbonate having [η] of 0.1 to 0.5 dl / g, and the polycarbonate obtained in the second polycondensation step
It has a horizontal rotary shaft and mutually discontinuous stirring blades mounted at a right angle to the horizontal rotary shaft, has no screw part, and the length of the horizontal rotary shaft is L. A polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 dl / g, which 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. And a third polycondensation reaction step for obtaining

According to the present invention, a high molecular weight polycarbonate having excellent mechanical properties and improved color tone can be produced.

Hereinafter, the method for producing a polycarbonate according to the present invention will be specifically described.

In the present invention, when producing a polycarbonate, an aromatic organic dihydroxy group compound and a carbonic acid diester are used.

The aromatic organic dihydroxy compound used in the present invention is represented by the following formula [I] (Where X is —O—, —S—, —SO— or —SO ₂ —, R ₁ and R ₂ are a hydrogen atom or a monovalent hydrocarbon group, and R ₃ is 2
Is a monovalent hydrocarbon group. The aromatic nucleus may have a monovalent hydrocarbon group. ).

Specific examples of such an aromatic organic dihydroxy group compound include bis (4-hydroxyphenyl) methane,
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-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-
Bis (hydroxyaryl) alkanes such as 1-methylphenyl) propane, 1,1-bis (4-hydroxy-t-butylphenyl) propane, and 2,2-bis (4-hydroxy-3-bromophenyl) propane; Bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, and 4,4′-
Dihydroxyaryl ethers such as dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethylphenyl ether, 4,4'-dihydroxyphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide, etc. Dihydroxydiaryl sulfides, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide and other dihydroxydiaryl sulfoxides, 4,4'-dihydroxydiphenyl sulfone, 4,
Dihydroxydiarylsulfones such as 4'-dihydroxy-3,3'-dimethyldiphenylsulfone are used.

Of these, 2,2-bis (4-hydroxyphenyl) propane is particularly preferred.

As the carbonic acid diester, specifically, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate and the like are used.

Of these, diphenyl carbonate is particularly preferred.

These carbonic acid diesters may contain a dicarboxylic acid or a dicarboxylic acid ester. Examples of such a dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate.

When a dicarboxylic acid or a dicarboxylic acid ester as described above is used in combination with a carbonic acid diester, a polyester polycarbonate is obtained. The method for producing a polycarbonate of the present invention also includes the method for producing a polyester polycarbonate.

In producing the polycarbonate in the present invention, the carbonic acid diester as described above is used in an amount of 1.01 to 1.30 mol, preferably 1.02 to 1.
Used in an amount of 20 moles.

In the present invention, when producing a polycarbonate by melt polycondensation of the aromatic organic dihydroxy group compound and diphenyl carbonates as described above, the number of carbon atoms as a terminal blocking agent in the reaction system is 17 to 50, preferably 17 to 50. 40 carbonic acid diesters are added in an amount of 0.05 to 10 mol%, preferably 0.5 to 7 mol%, more preferably 1 to 5
It is also possible to prepare in the presence of mol%.

As a carbonic acid diester having 17 to 50 carbon atoms as an end capping agent, the general formula Wherein A is a group having 6 to 25 carbon atoms, and B is a group having 10 to carbon atoms.
There are 25 groups. ) Is used.

As the carbonic acid diester as described above, specifically,
The following compounds are used.

(Wherein, R ¹ is a hydrocarbon group having 3 to 18 carbon atoms) (Wherein, R ² and R ³ may be the same or different, and R ² is a hydrocarbon group having 1 to 19 carbon atoms and R ³ is a hydrocarbon group having 4 to 19 carbon atoms) (Wherein, R ⁴ is a hydrocarbon group having a carbon number of 1 to 17, R ⁵
It is a hydrocarbon group having 1 to 11 carbon atoms.) (Wherein, R ⁶ is a hydrocarbon group having 4 to 19 carbon atoms) (Wherein R ⁷ and R ⁸ may be the same or different, and R ⁷ is a hydrocarbon group having 1 to 19 carbon atoms and R ⁸ is a hydrocarbon group having 3 to 18 carbon atoms) As the carbonic acid diester as the terminal blocking agent used in the present invention as described above, more specifically, the following compounds are preferably used.

Carbobutoxy phenyl phenyl carbonate, methyl phenyl butyl phenyl carbonate, ethyl phenyl butyl phenyl carbonate, dibutyl diphenyl carbonate, biphenyl phenyl carbonate, dibiphenyl carbonate, cumyl phenyl phenyl carbonate, dicumyl phenyl carbonate, naphthyl phenyl phenyl carbonate, dinaphthyl phenyl carbonate , Carboxypropoxyphenylphenyl carbonate, carboheptoxyphenylphenyl carbonate,
Carbomethoxy t-butylphenylphenyl carbonate, carboprotoxyphenylmethylphenylphenyl carbonate, and the like.

When such a carbonic acid diester is used as a terminal blocking agent, the entire amount may be added to the reaction system in advance, or a part thereof may be added to the reaction system in advance, and the remainder may be added as the reaction proceeds. You may. Further, in some cases, the whole amount may be added to the reaction system after the polycondensation reaction between the aromatic organic dihydroxy compound and the carbonic acid diester partially proceeds.

In the present invention, an alkylphenol having 10 to 40 carbon atoms, preferably 15 to 40 carbon atoms, is used as a terminal blocking agent in the reaction system.
0.05 to 10 mol%, preferably 0.5 to 7 mol%, more preferably 1 to 5 mol%, based on the aromatic organic dihydroxy group compound
To produce polycarbonate.

In the present invention, the following compounds are used as alkylphenols having 10 to 40 carbon atoms.

on-butylphenol mn-butylphenol pn-butylphenol o-isobutylphenol m-isobutylphenol p-isobutylphenol ot-butylphenol mt-butylphenol pt-butylphenol on-pentylphenol m- n-pentylphenol p-n-pentylphenol o-n-hexylphenol m-n-hexylphenol p-n-hexylphenol o-cyclohexylphenol m-cyclohexylphenol p-cyclohexylphenol o-phenylphenol m-phenylphenol p- Phenylphenol on-nonylphenol mn-nonylphenol pn-nonylphenol o-cumylphenol m-cumylphenol p-cumylfe O-naphthylphenol m-naphthylphenol p-naphthylphenol 2,6-di-t-butylphenol 2,5-di-t-butylphenol 2,4-di-t-butylphenol 3,5-di-t-butylphenol 2,5-Dicumylphenol 3,5-Dicumylphenol These are monovalent phenols having such a structure.

Among such alkylphenols, the aromatic nucleus is 2
Dinuclear phenols are preferred, and p-cumylphenol, p-phenylphenol and the like are particularly preferred.

When such an alkyl phenol is used as a terminal blocking agent, the entire amount may be added to the reaction system in advance, or a part of the alkyl phenol may be added to the reaction system in advance, and the remainder is added as the reaction proceeds. May be. In some cases,
After the polycondensation reaction between the aromatic organic dihydroxy group compound and the carbonic acid diester partially proceeds, the whole amount may be added to the reaction system.

In the present invention, when a polycarbonate is produced by melt-polycondensation of an aromatic organic dihydroxy group compound and a carbonic acid diester as described above, a conventionally known catalyst or a catalyst newly developed by the present applicant is used. Can be. For example, Japanese Patent Publication No. 36-694 or Japanese Patent Publication
6-13942 catalyst, specifically, alkali metals such as lithium, sodium and potassium, magnesium, calcium, alkaline earth metals such as barium, zinc, cadmium, tin, antimony, lead, manganese, Acetates, carbonates of metals such as cobalt and nickel,
Borates, oxides, hydroxides, hydrides, alcoholates and the like are used, and a nitrogen-containing basic compound and boric acid or boric acid esters, phosphorus compounds and the like are used. Furthermore, titanates, benzenesulfonates, and the like are also used.

These catalysts are preferably used in an amount of 10 ^-6 to 10 ^-1 mol, preferably 10 ^-5 to 10 ^-2 mol, per 1 mol of the aromatic organic dihydroxy compound used as a raw material.

 Hereinafter, particularly preferred catalyst systems will be described in detail.

In the present invention, when a polycarbonate is produced by melt polycondensation of an aromatic organic dihydroxy group compound and a carbonic acid diester, (a) a nitrogen-containing basic compound, (b) an alkali metal compound or an alkaline earth metal compound, (c) Among the boric acid or borate ester, a catalyst comprising (a) and (b), (a) and (c), (b) and (c) or (a), (b) and (c) may be used. Particularly preferred.

(A) Specific examples of the nitrogen-containing basic compound include tetramethylammonium hydroxide (Me ₄ NOH), tetraethylammonium hydroxide (Et ₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), and trimethylbenzyl. Ammonium hydroxide Such as tetraalkyl or aryl, araryl ammonium hydroxides, tertiary amines such as trimethylamine, triethylamine, dimethylbenzylamine, triphenylamine, R ₂ NH (wherein R is alkyl such as methyl or ethyl, phenyl, toluyl) Secondary amines represented by (such as aryl groups), primary amines represented by RNH ₂ (wherein R is the same as above), or ammonia, tetramethylammonium borohydride (Me ₄ NBH ₄ ). , Basic salts such as tetrabutylammonium borohydride (Bu ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Bu ₄ NBPh ₄ ), tetramethylammonium tetraphenylborate (Me ₄ NBPh ₄ ), etc. are used.

Of these, tetraalkylammonium hydroxides are particularly preferred.

(B) Specific 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 and the like are used.

Specific examples of the alkaline earth metal compound (b) include calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, and carbonate. Calcium, 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 are used.

Examples of (c) boric acid or boric acid ester include boric acid or the general formula B (OR) _n (OH) _3-n (wherein R is alkyl such as methyl and ethyl, aryl such as phenyl, and the like). Is 1, 2 or 3).

Specific examples of such borate esters include trimethyl borate, triethyl borate, tributyl borate, trihexyl borate, triheptyl borate, triphenyl borate, tritolyl borate, and trinaphthyl borate. .

When the above-mentioned (a) nitrogen-containing basic compound is used, 1 mol of the aromatic organic dihydroxy group compound is used.
In an amount of 10 ^-6 to 10 ^-1 mol, preferably 10 ^-5 to 10 ^-2 mol,
(B) When an alkali metal compound or an alkaline earth metal compound is used, 10 ^-8 to 10 ^-3 mol, preferably 10 ^-7 to 10 mol
10 ^-4 mol, particularly preferably used in 10 ^-6 to 10 ^-4 molar amounts in an amount, and (c) boric acid or 10 ^-8 10 ^-1 mole If boric acid ester is preferably used 10 ^- It is used in an amount of ⁷ to 10 ^-2 mol, particularly preferably in an amount of 10 ^-6 to 10 ^-3 mol.

When the amount of the nitrogen-containing basic compound (a) is less than 10 ^-6 mol per 1 mol of the aromatic organic dihydroxyl compound, the transesterification reaction and the polymerization reaction are delayed, and therefore the alkali metal compound or the alkaline earth metal compound is used. Of the resulting polycarbonate, as a result, the hue, heat resistance, water resistance, etc. of the polycarbonate obtained tends to decrease, while if it exceeds 10 ^-1 mol, the hue and water resistance of the polycarbonate obtained, etc. Tends to decrease.

(B) an alkali metal compound or an alkaline earth metal compound is added to 1 mole of an aromatic organic dihydroxy compound;
10 is less than ^-8 mole, polymerization activity, especially caused a tendency that the polymerization rate at high temperature is significantly decreased, whereas more than 10 ^-3 mol, the polymerization activity is improved, the obtained polycarbonate hue, heat resistance , Water resistance tends to decrease.

If the amount of (c) boric acid or boric acid ester is less than 10 ^-8 mol per 1 mol of the aromatic organic dihydric group compound, the molecular weight after thermal aging tends to decrease significantly,
On the other hand, if it exceeds 10 ^-1 mol, the water resistance of the obtained polycarbonate tends to decrease.

Thus, (a) a nitrogen-containing basic compound, (b) an alkali metal compound or an alkaline earth metal compound, and (c)
Among the boric acids or borate esters, catalysts consisting of (a) and (b), (a) and (c), (b) and (c) or (a), (b) and (c) have high polymerization The polycarbonate having an activity can produce a high-molecular-weight polycarbonate, and the obtained polycarbonate has excellent heat resistance and water resistance, and further has improved color tone and excellent transparency.

Next, a method for producing a polycarbonate according to the present invention will be described with reference to the drawings.

FIG. 1 is an example of a typical process chart for carrying out the method for producing a polycarbonate according to the present invention.

[First Polycondensation Reaction Step] First, for example, bisphenol A, which is an aromatic organic dihydroxy group compound, and diphenyl carbonate, which is a carbonic acid diester, are melted in a tank type stirring tank 1 under a nitrogen purge in a molten state. The raw material is introduced through a raw material introduction tube 2, 3 (4, 5 when diphenyl terephthalate or diphenyl isophthalate is used), and these raw material monomers are sufficiently stirred and mixed. The monomer mixture is transferred to the raw material transfer conduit 6.
, And is supplied to a tank-type reaction tank 7 having a vertical rotation shaft and a stirring blade attached to the vertical rotation shaft.

The tank-type reaction tank 7 includes at least one or more turbine blades, paddle blades, anchor blades, helical ribbon blades, or blades obtained by improving these blades. In the present invention, at least one or more such tank-type reaction tanks are used.

In the above-mentioned tank-type reaction tank 7 whose transesterification reaction start temperature was controlled, a small amount of boric acid or boric acid ester dissolved in a monomer, phenol or the like was introduced into the introduction pipe
Is continuously supplied to the tank-type reaction tank 7 through the tank to perform stirring.

Next, this reaction mixture will be described later via the raw material transfer conduit 9 while adding a small amount of the nitrogen-containing basic compound and / or the alkali metal compound or the alkaline earth metal compound through the catalyst introduction pipe 8 '. The reaction mixture is supplied to a tank-type reaction tank 10 that is controlled under temperature and pressure conditions suitable for carrying out the first polycondensation reaction as described above, and the reaction mixture is further reacted to obtain a polycarbonate.

The reaction temperature in the first polycondensation reaction is usually 50 to 27.
0 ° C, preferably in the range of 150 to 260 ° C, and the pressure can be reduced from atmospheric pressure to 6 mmHg, and the lower limit pressure of the reduced pressure condition in this case is 400 to 6 mmHg, preferably 300 to 6
It can be set in the range of mmHg.

In this first polycondensation reaction step, a polycarbonate having an intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C. of 0.01 to 0.4 dl / g, preferably 0.03 to 0.35 dl / g is obtained.

In addition, the vapor of the phenol by-produced in this reaction and the vapor of a part of the unreacted monomer are introduced into the distillation column 11 via the conduit 13 and brought into contact with the reflux phenol supplied via the reflux phenol conduit 16. To rectify. The rectified unreacted monomer is supplied again to the tank-type reaction tank 10 via the conduit 14. On the other hand, the phenol vapor is introduced into the condenser 12 via the phenol paper conduit 15 and condensed. Part of the condensed phenol is introduced into the distillation column 11 as reflux, the remaining phenol is removed to the outside of the system through the phenol recovery conduit 17, and uncondensed phenol is cold through the vent conduit 18. Collected in a trap.

[Second Polycondensation Reaction Step] Next, the polycarbonate obtained in the first polycondensation step is supplied to the centrifugal thin-film type evaporator 20 through the prepolymer transfer conduit 19 to perform a first polycondensation step as described below. Under a temperature and pressure condition suitable for carrying out the double condensation reaction, the by-produced phenol and a part of unreacted monomer are removed from the system through the vent conduit 21 to carry out the polycondensation reaction.

This centrifugal thin-film type evaporator 20 forms a thin film of the reaction solution on the heat transfer surface by mechanical centrifugal force of the reaction solution, inertial force of the reaction solution, a dispersion device, etc., and is a thin film of a method of promoting evaporation of phenol and monomer. Type evaporator. In the present invention, at least one thin film evaporator such as a centrifugal thin film evaporator is used.

The reaction temperature in the second polycondensation reaction is usually 180 to 2
The temperature is 85 ° C, preferably 200 to 270 ° C, and the pressure is 1 to 50 mmHg, preferably 1 to 30 mmHg.

In this second polycondensation reaction step, the intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C. is 0.1 to 0.5 dl / g, preferably 0.15 to 0.45 dl / g, and more preferably 0.15 to 0.4 dl / g. Get a Polycarbonate.

In the reaction apparatus of the present invention in which the reaction is carried out until the intrinsic viscosity [η] of the polycarbonate produced in the first polycondensation reaction step and / or the second polycondensation reaction step reaches 0.3 dl / g, the viewpoint of the color tone of the polycarbonate From
At least 90% of the total surface area of the wetted part is at least 90% of the total surface area of the wetted part
It is preferable to be composed of one or more of glass, nickel, tantalum, chromium, and Teflon in a proportion occupying the above. In the present invention, it is sufficient that the surface material of the liquid contact part is made of the above-mentioned substance, and a bonding material composed of the above-mentioned substance and another substance, or a material obtained by plating the above-mentioned substance on another substance is used as the surface material. Can be used.

[Third Polycondensation Reaction Step] Next, the polycarbonate obtained in the second polycondensation reaction step is attached to a horizontal rotation shaft and a substantially right angle to the horizontal rotation shaft via the prepolymer transfer conduit 22. L / D is 1 to 1 where L is the length of the horizontal rotating shaft and D is the rotating diameter of the stirring blade.
It is supplied to the horizontal stirring polymerization tank 23, which is No. 5, and under the temperature and pressure conditions of the third polycondensation reaction, the by-produced phenol and some unreacted monomers are removed to the outside of the system through the vent conduit 24, and the heavy polymer Conduct a condensation reaction.

The horizontal stirring polymerization tank 23 has one or two or more horizontal rotating shafts, and the horizontal rotating shaft is provided with a stirring blade of disc type, wheel type, paddle type, rod type, window frame type or the like. It is a horizontal high-viscosity liquid processing apparatus which is installed in at least two stages per rotary shaft in combination with two or more kinds, and which stirs or spreads the reaction solution by this stirring blade to renew the surface of the reaction solution, In the present specification, the term "renewal of the surface of the reaction solution" means that the reaction solution on the surface of the liquid is replaced with the reaction solution below the surface of the liquid. Thus, the horizontal stirring polymerization tank used in the present invention is a device having a horizontal axis and mutually discontinuous stirring blades attached at substantially right angles to the horizontal axis, and unlike an extruder, a screw part is provided. I don't have it. In the present invention, at least one or more such horizontal stirring polymerization tanks are used.

The reaction temperature in the third polycondensation reaction is usually 240 to 3
20 ° C., preferably in the range of 250-290 ° C., and the pressure is
It is 4 mmHg or less, preferably 2 mmHg or less.

The horizontal stirring polymerization tank used in the present invention is
Since the hold-up is large as compared with the twin-screw vented extruder, the reaction conditions (particularly the temperature) can be lowered by extending the residence time of the reaction mixture, and the color tone is improved and the mechanical properties are excellent. It becomes possible to obtain polycarbonate.

In this third polycondensation reaction step, the intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C is 0.3 to 1.0 dl / g, preferably 0.33 to 0.9 dl / g, more preferably 0.35 to 0.8 dl / g. To obtain polycarbonate.

In the present invention, a twin-screw vent type extruder may be used after carrying out the polycondensation reaction in a horizontal stirring polymerization tank. When the twin-screw vent type extruder is used in the present invention, the polycondensation reaction is considerably advanced in the horizontal stirring polymerization tank in the preceding stage, so that the reaction conditions of the twin-screw vent extruder can be relaxed, and the quality of the polycarbonate is improved. It is possible to prevent deterioration.

Effect of the Invention According to the present invention, a mixture of an aromatic organic dihydroxyl compound and a carbonic acid diester is melted, a polycondensation reaction is carried out in a specific tank type reaction tank, and measured in a methylene chloride solution at 20 ° C. A first polycondensation reaction step for obtaining a polycarbonate having an intrinsic viscosity [η] of 0.05 to 0.4 dl / g, wherein the polycarbonate obtained in the first polycondensation step is
The polycondensation reaction was carried out in a specific thin film type evaporator to obtain a polycarbonate having an intrinsic viscosity [η] of 0.1 to 0.5 dl / g. The second polycondensation reaction step and the second polycondensation step. Polycarbonate,
Polycarbonate is produced through a third polycondensation reaction step in which a polycondensation reaction is carried out in a specific horizontal stirring polymerization tank to obtain a polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 dl / g. A high-molecular-weight polycarbonate having properties and improved color is obtained.

Hereinafter, the present invention will be described with reference to examples, the present invention,
It is not limited to these examples.

First, test methods of intrinsic viscosity [η], hue [b value], haze, light transmittance, Izod impact strength (with notch), and terminal hydroxyl group concentration of the polymers obtained in Examples and Comparative Examples are shown below.

[Test method] (1) Intrinsic viscosity [η]: Measured in methylene chloride at 20 ° C using an Ubbelohde viscometer.

(2) Hue [b value]: The Lab value of a 2 mm thick press sheet was calculated using the Nippon Denshoku Industries Co., Ltd. Color and Color Defference Meter.
It was measured by a transmission method using ND-1001D, and the b value was used as a measure of yellowness.

(3) Haze, (4) Light transmittance: Measured with an automatic digital haze meter NDH-20D of Nippon Denshoku Industries Co., Ltd. using a 2 mm thick press sheet.

(5) Izod impact strength (with notch): Using a press plate having a thickness of 2 mm, it was measured according to ASTM D 256 using YSI-3D manufactured by Yonekura Co., Ltd.

(6) Terminal hydroxyl group concentration: A sample of 0.4 g was dissolved in 3 ml of chloroform, and ^13C -NMR of JEOL Ltd. was carried out at 40 ° C.
It was measured by GX-270.

Example 1 0.44 kmol of bisphenol A and 0.49 kmole of diphenyl carbonate were charged into a 250-liter stirred tank, and after displacing with nitrogen, were dissolved at 140 ° C. Then this one
The temperature is raised to 80 ° C., 0.11 mol of boric acid is added, and the mixture is stirred for 30 minutes. Next, 0.11 mol of tetramethylammonium hydroxide and 0.003 mol of sodium hydrogencarbonate were added as catalysts, and the temperature was raised to 240 ° C. and, at the same time, the pressure was gradually lowered to 15 mmHg. The temperature and pressure were kept constant, and the amount of phenol distilled out was measured. When there was no more phenol distilled out, the pressure was returned to atmospheric pressure with nitrogen. The time required for the reaction was 2 hours. Intrinsic viscosity [η] of the obtained reaction product
Was 0.15.

Next, the pressure of this reaction product was increased by a gear pump, and the reaction product was sent to a centrifugal thin film evaporator to proceed the reaction. The temperature and pressure of the thin film evaporator were controlled at 260 ° C and 4 mmHg, respectively. The prepolymer extracted from the lower part of the evaporator with a gear pump was passed through a die into a strand in a nitrogen atmosphere, cut into a pellet with a cutter. The intrinsic viscosity [η] of this prepolymer was 0.35.

Next, this prepolymer was fed into a biaxial horizontal stirring polymerization tank (L / D = 6, stirring blade rotating diameter 150 mm, internal volume 40 liters) controlled at 280 ° C. and 0.4 mmHg at 20 kg / hour with an extruder and retained. Polymerization was carried out for 60 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.62.

 Table 1 shows other test results.

Example 2 Polymerization was carried out under the same conditions as in Example 1 except that boric acid was changed to 0.05 mol and tetramethylammonium hydroxide was changed to 0.05 mol, and a polymer was obtained. Was done.

 Table 1 shows the results.

Example 3 In Example 1, 2-carbomethoxy-5-t-butylphenylphenyl carbonate was used as a terminal blocking agent in a prepolymer obtained by a two-stage polycondensation reaction at a ratio of 5 mol% to bisphenol A. Polymerization was carried out under the same conditions as in Example 1 except that addition, mixing and feeding into a biaxial horizontal stirring polymerization tank using an extruder were performed to obtain a polymer, and the above polymer was subjected to the above test.

 Table 1 shows the results.

Example 4 Polymerization was carried out under the same conditions as in Example 1 except that paracumylphenol as an end-capping agent was mixed with bisphenol A as a raw material at a ratio of 5 mol% with respect to bisphenol A. Was obtained, and the above-mentioned test was performed on the obtained polymer.

 Table 1 shows the results.

Comparative Example 1 Two-step polycondensation was carried out in the same manner as in Example 1 to obtain a prepolymer having an intrinsic viscosity [η] of 0.35. The prepolymer was fed to a twin-screw vent type extruder (35 mm L / D = 30, rotating in the same direction) at 5 kg / hour. At this time, the temperature of the cylinder
At 280 ° C, the pressure at the vent was controlled to 0.4 mmHg.
The residence time at this time was 4 minutes. The intrinsic viscosity [η] of the obtained polymer was 0.47.

 Table 1 shows other test results.

Comparative Example 2 Polymerization was carried out under the same conditions as in Comparative Example 1 except that 0.22 mol of boric acid, 0.22 mol of tetramethylammonium hydroxide and 0.006 mol of sodium hydrogen carbonate were added as a catalyst to obtain a polymer. The above test was performed on the obtained polymer.

 Table 1 shows the results.

Comparative Example 3 In Example 1, the obtained prepolymer pellets after the second-stage polycondensation reaction were sent to a centrifugal thin-film evaporator controlled at a temperature of 280 ° C. and a pressure of 0.4 mmHg using an extruder to be reacted. The intrinsic viscosity [η] of the obtained polymer is
It was 0.60.

 Table 1 shows other test results.

[Brief description of the drawings]

FIG. 1 is an example of a typical process chart for carrying out the method for producing a polycarbonate according to the present invention. 1 ... Tank-type stirring tank 2,3,4,5 ... Raw material introduction pipe 7 ... Tank-type reaction tank 8,8 '... Catalyst introduction pipe, 11 ... Distillation column 12 ... Condenser 17 ... Phenol Recovery conduit 18 …… Vent conduit 20 …… Centrifugal thin film evaporator 21 …… Vent conduit 23 …… Horizontal stirring polymerization tank 24 …… Vent conduit 25 …… Outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasujiro Shigeta 6-1-2 Waki, Waki-cho, Kuga-gun, Yamaguchi Mitsui Petrochemical Industry Co., Ltd. (56) Reference Japanese Patent Publication Sho 53-5718 (JP, B2)

Claims (1)

(57) [Claims] 1. When producing a polycarbonate by melt polycondensation of an aromatic organic dihydroxyl compound and a carbonic acid diester, a vertical rotating shaft and stirring attached to the vertical rotating shaft are melted while the above monomer mixture is melted. Polycarbonate having an intrinsic viscosity [η] of 0.05 to 0.4 dl / g measured in a methylene chloride solution at 20 ° C. by supplying it to at least one or more tank type reaction vessels equipped with blades to carry out polycondensation reaction. The first polycondensation reaction step to be obtained, and at least the polycarbonate obtained in the first polycondensation step is formed into a thin film of this polycarbonate, and at the same time distillates such as phenol produced by the reaction and partially unreacted monomers are evaporated. It is supplied to one or more thin film type evaporators to carry out a polycondensation reaction to obtain the above-mentioned intrinsic viscosity [η].
In the second polycondensation reaction step to obtain a polycarbonate having a value of 0.1 to 0.5 dl / g, the polycarbonate obtained in the second polycondensation step, and At least L / D is 1 to 15 when the horizontal axis of rotation is L and the rotational diameter of the stirring blade is D. It is characterized by comprising a third polycondensation reaction step in which the polycondensation reaction is carried out by supplying to one or more horizontal stirring polymerization tanks to obtain a polycarbonate having an intrinsic viscosity [η] of 0.3 to 1.0 dl / g. Method for producing polycarbonate.