JP3219923B2 - Production method of polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an aqueous alkali metal salt solution of diphenol from a raw material containing phosgene, diphenol, a molecular chain terminator and an optional branching agent by dissolving an aromatic oligocarbonate and an aromatic polycarbonate and by itself dissolving water. In the presence of a solvent or solvent mixture immiscible with
The present invention relates to a method for producing a thermoplastic aromatic polycarbonate by a phase interface condensation method in which phosgenation is carried out using a polycondensation catalyst and three reactors arranged in series at a pH value of 14.

In the production of polycarbonate by the phase interface method, it is important to control the reaction so that a high yield of raw materials and good phase separation are achieved. A high raw material yield is advantageous not only from an economical point of view but also from an ecological point of view. Good phase separation is a prerequisite for obtaining high quality of the product.

[0003] Thus, German Offenlegungsschrift 2,305,144
No. describes a continuous process for the production of polycarbonate in which an aqueous diphenol solution is combined with phosgene in the presence of an amine in a mixing zone and then phosgenation proceeds in the first part of the reaction path. Subsequently, the solvent is added only in the second part of the reactor to complete the reaction. One disadvantage of this method is the use of a large excess of phosgene and a large amount of aqueous reaction phase, which must be treated as waste. A large amount of aqueous reaction phase also promotes phosgene side reactions.

According to DE-A-2,434,939, the properties of polycarbonates produced by the two-phase interface method are improved by controlling the reaction by adjusting the pH. The large excess of phosgene used is disadvantageous and the process is not continuous.

According to the teaching of European Patent No. 282,546, diphenol / water /
If the sodium hydroxide suspension and phosgene are introduced simultaneously and continuously into the organic phase contained in the reactor and the reaction product is subsequently separated, the condensate containing the chloroformyl end groups has a high phosgene yield. Is obtained. During this reaction, the pH was 2
Adjusted to a value of ~ 5.

The disadvantages here are the technical difficulties of feeding the suspension and the low pH which considerably increases the time required for phosgenation. No means for polycondensation is described.

According to European Patent No. 434,888, a polycarbonate having improved thermal stability and improved color is obtained when the process is carried out with a water / oil emulsion containing specially sized droplets. Can be

European Patent No. 263,432 discloses that condensates containing chloroformyl end groups, ie polycarbonates, can be obtained from aqueous diphenolate and organic phosgene solutions at pH values of 8 to 11 and at temperatures of 15 to 50 ° C. and at least 10 It is disclosed that it is prepared by mixing the phases under a phosgene excess of mol% and proceeding the phosgenation while adding an alkali metal or alkaline earth liquid. The preferred phase ratio is from 0.4: 1 to 1: 1 water: oil, which is maintained by subsequent addition of water.

DE-A-2,725,967 discloses that the phosgene yield of a continuous process is such that aqueous alkali metal diphenol solutions are first combined with an organic phosgene solution in a tube and then these components are added to a tank reactor. To be advantageous. The residence time in the pipe is 0.5 to 15
Should be seconds. This process has the disadvantage that the phosgenation takes place at an unfavorable phase ratio (oil: water = 0.2-1) to cause phase separation after the end of the reaction.

According to European Patent No. 306,838 A2, phosgene is monitored in situ using an automatic chloride detector. Chemical variations in the reaction are detected and offset in this way. The industrial properties of the polycarbonate are improved. The basic idea of this method is to return unreacted diphenolate to the process. However, one disadvantage of this method lies in the cumbersome step of recycling the unreacted diphenol and the side reaction of phosgene.

According to European Patent No. 339,503 A2, the side reactions of phosgene are increased, especially if the sodium hydroxide solution has a high initial concentration. In this patent specification, therefore, diphenol / sodium hydroxide / water solution is added to the organic phenol solution at an alkali metal / diphenol ratio of 2: 1 or less (less than the equivalent of alkali),
Then, an oligomer having a molecular weight of 300 to 3000 g / mol is produced in the first reaction stage. The water / oil phase ratio is greater than 1 and therefore the water consumption is high. Furthermore, phosgene side reactions are still undesirable.

According to European Patent No. 305,691 A2, fine emulsions obtained by vigorous mixing are:
It is advantageous to allow the reaction to proceed in a two-phase interface method, while allowing very high phosgene excess (20-100 mol%). The large amount of phosgene introduced into the reactor ensures good phase separation despite vigorous mixing of the emulsion at the beginning of the reaction. However, the yield of phosgene is quite unsatisfactory.

US Pat. No. 4,847,352, US Pat.
According to 37,941 and 5,037,942, the reactants are mixed in a static mixer to produce a fine aqueous dispersion, followed by a coarse dispersion. These dispersion and reaction steps are repeated until the reaction is complete.

The continuous production of polycarbonates by the phase interface method often requires a large excess of phosgene and / or unfavorable phase ratios and often requires high amounts of water since separation and washing problems occur otherwise after the end of the reaction. I need.

A satisfactory phase separation effect is achieved by using a large amount of water in the reaction. However, this comes at the expense of raw material yield, and thus product quality and reproducibility of product properties.

At present, surprisingly, the production of polycarbonate by the phase interface method requires a high yield of raw materials and a constant molecular weight if the whole process is carried out using an oil / water emulsion having a high electrolyte content in the aqueous phase. It has been found to proceed very economically with reproducibility and excellent separation of the reaction emulsion.

The process according to the invention is characterized in that the aqueous reaction phase obtained after the end of the reaction is combined with the raw materials in a quantity such that an oil / water emulsion is formed directly and is maintained over the entire reaction time. It is unique that it is returned to the container partially. Surprisingly, it has been found that the side reactions discussed in the literature are not promoted by a large amount of aqueous phase at high electrolyte contents. Conversely, the amount of raw materials can be reduced.

The process according to the invention surprisingly results in a continuously reproducible phase separation, with only small amounts of water remaining in the organic phase. Further advantages have been found in washing the crude polycarbonate solution to remove the electrolyte. Reaction with additives during the extrusion process is suppressed. Furthermore, the molecular weights obtained in the continuous process can be kept within narrow limits. It is also advantageous that a high concentration of an aqueous alkali metal salt solution of diphenol can be used to reduce the amount of waste liquid. It is another advantage that the excess of phosgene can be substantially reduced without losing the quality of the polycarbonate and / or without increasing the diphenol and phenol content in the aqueous reaction phase. The specific amount of salt in the effluent and the amount of di- and monophenols in the effluent are also reduced.

The diphenols which can be used for the preparation of the high molecular weight polycarbonates according to the process of the invention are those which form water-soluble alkali metal salts with alkali metal hydroxides, such as sodium or potassium hydroxide. Alkaline earth solutions can also be used. This condition applies to virtually all known diphenols and mixtures thereof.

Corresponds to the general formula HO-Z-OH, provided that Z
Diphenols which exhibit one or more aromatic nuclei, which may have different substituents, are preferred. The substituents can be aliphatic or cycloaliphatic groups or water, chlorine or bromine. A bridging member or heteroatom which may contain an aliphatic or alicyclic group may be present between the two aromatic nuclei. The following are examples: hydroquinone, resorcinol, dihydroxydiphenol, bis- (hydroxyphenyl) -alkane, bis- (hydroxyphenyl) -cycloalkane, bis- (hydroxyphenyl) -sulfide, bis- ( (Hydroxyphenyl) -ether, bis- (hydroxyphenyl) -ketone, bis- (hydroxyphenyl) -sulfone, bis- (hydroxyphenyl) -sulfoxide, 1,1′-bis- (hydroxyphenyl)-
Diisopropylbenzene and alkyl or halogen nucleus substituted derivatives thereof.

These and other suitable diphenols are
For example, U.S. Patent Nos. 4,982,014 and 3,028,3
No. 65, No. 2,999,835, No. 3,148,172
No. 3,275,601, No. 2,991,273, No. 3,271,367, No. 3,062,781, No. 2,9
Nos. 70,131 and 2,999,846, German Patent Nos. 1570703, 2063050, 206
Nos. 3052 and 2211956 and French Patent 1,561,518.

Suitable diphenols are in particular 2,2-bis-
(4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, 1,1-bis- (4-hydroxyphenyl)-
Cyclohexane and 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

The amount and type of molecular chain terminator and optional branching agent can be added to the diphenol before, during or after hesgenation, but before reacting to high molecular weight polycarbonate. Suitable chain terminators include known monophenols such as phenol itself, C ₁ -C ₁₀ alkyl phenols such as p-tert-butylphenyl and p-phenyl.
-Cresol and halogenated phenols such as p-chlorophenol and 2,4,6-tribromophenol. Phenol, cumylphenol, isooctylphenol and p-tert-butylphenol are preferred chain stoppers.

The number of branching agents used is 3 or 4 or 4
Those having two or more functional groups, particularly those having three or more than three phenolic hydroxyl groups. The amounts of these compounds are usually the values observed for the branching agents of the 0.1.
It should be kept in the range of 0.5 to 2 mol%. However, these percentages are based on the amount of diphenols introduced.

The following are some examples of suitable branching agents having three or more phenolic hydroxyl groups:
2,4-bis- (4-hydroxyphenyl-isopropyl) -phenol, 2,6-bis- (2'-hydroxy-5'-methylbenzyl) -4-methylphenol, 2
-(4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) -propane, 1,1,1-tris- [4
-Hydroxyphenyl) -ethane and 1,4-bis-
(4,4'-dihydroxytriphenyl-methyl) -benzene. Further examples of trifunctional compounds are 2,4-dihydroxybenzoic acid, trimellitic acid, sialic acid chloride, 3,3-bis- (4-hydroxyphenyl) -2-
Oxo-2,3-dihydroindole and 3,3-bis-
(4-Hydroxy-3-methyl-phenyl) -2-oxo-2,3-dihydroindole.

The solvent which can be used can be any solvent which dissolves the oligo and the polycarbonate at the chosen reaction temperature and pressure and which is substantially immiscible with water (in the sense of a solution). Chlorinated hydrocarbons such as methylene chloride and / or dichlorobenzene are preferably used.

These solvents can be used alone or in a mixture of various compositions. If chlorobenzene is used alone, it is necessary to use high operating temperatures for the reaction and for the washing in order to obtain an industrially useful concentration of polycarbonate in chlorobenzene. Benzene homologs may also be used as solvents.

A suitable solvent combination for the technically important polycarbonates based on 2,2-bis- (4-hydroxyphenyl) -propane is a mixture of methylene chloride and toluene, which comprises all process steps. Can be used in The concentration of the polycarbonate in the solution containing the solvent is 5
３０30%.

Among the many polycondensation catalysts described for the phase interface method, among the trialkylamines, N-ethyl-pyrrolidone, N-ethylpyrrolidone, N-ethylpiperidine,
Particular mention is made of N-ethylmorpholin, N-isopropylpiperidine and N-isopropylmorpholin.
Triethylamine and N-ethylpiperidine are particularly suitable.

Reaction loops containing heat exchangers, heat controlled vessels with stirrers and various forms of heat controllable flow tubes are suitable reactors. The ability to stir vigorously at all times and throughout the apparatus is common to all reactors. Suitable flow tubes are designed to provide the required residence time in the residence and mixing zones. This type of flow tube is mainly described in German Patent Publication No.
No. 2 and U.S. Pat. No. 3,674,740. Various static mixers on the market are also suitable for maintaining the emulsion. A preferred series arrangement of these reactors is used in the process of the invention and comprises one pump circulation reactor and two residence reactors arranged in series (German Patent Publication No. 1920302). reference). However, each of these reactors has a mixing and retention zone.

It has been found that two pump circulation reactors arranged in series, followed by one flow tube, are also satisfactory.

In all the reaction steps, the pH is between 8 and
14, preferably 10 to 13.5. These values are achieved by introducing a portion of the total amount of sodium hydroxide required in the pump circulation reactor and adding the remainder before entering the second or third reactor.

The average residence time depends on the type of reactor used. Generally, only the flow tube requires a short residence time. The residence time is generally a few seconds to 30 minutes. Short residence times are advantageous over the initial reaction time. These ranges are from 10 seconds to 30 minutes, preferably from 10 seconds to 15 minutes. A residence time of 1 to 30 minutes, preferably 2 to 15 minutes for the second reaction stage and a residence time of 2 to 30 minutes, preferably 2 to 15 minutes for the third reaction stage is selected. The residence time depends very much on the intensity of mixing in the reactor used and on the diphenols introduced into the process.

In one embodiment shown in any of the embodiments, the method of the present invention is performed in the following three stages. In the first stage, the aqueous alkali metal salt solution of diphenol is reacted with phosgene in the presence of an organic solvent, and the recycled aqueous reaction phase and any additional alkali metal liquid and intermediates added with some time delay The composition may be a second
In the step, the reaction with the monophenol and the further amount of sodium hydroxide solution is continued, then the intermediate product obtained in this second step is condensed in the third step, and the polycarbonate is reduced in the presence of a polycondensation catalyst. Manufacturing is a feature.

In the process according to the invention, the concentration of diphenol in the aqueous alkali metal solution is advantageously from 10 to 40% by weight, preferably from 15 to 30% by weight, based on the aqueous alkali metal solution.

In the process of the present invention, the aqueous reaction phase has a diphenol concentration of 2.5 to 25% by weight based on the total reaction phase consisting of the alkali metal salt solution, the alkali liquid and the recycled aqueous reaction phase. , Preferably 2.5
It is advantageous if it is returned in an amount corresponding to 〜15% by weight, most preferably 2.5-10% by weight.

In the process according to the invention, the reaction is carried out in such an amount that the lowest boiling solvent does not reach the boiling point in the reactor at normal pressure without further cooling of the aqueous reaction phase in the case of a solvent or in the case of a solvent mixture. It is advantageous to control it to be returned and pre-cooled to such a degree.

In a preferred method of conducting the reaction, the solvent or solvent mixture is selected to have a boiling point above the temperature at which it would be established in the reaction mixture without pre-cooling of the recycled aqueous reaction phase, and Cooling can generally be omitted.

A preferred embodiment of the method is described below.
Alkaline aqueous diphenol solution, recirculated aqueous reaction phase (amount that always guarantees a whole oil / water emulsion), phosgene with solvent and sodium hydroxide solution added at staggered time to maintain pH 8-14 Is introduced into the emulsion which is pumped through the reaction coil. After leaving the reactor, an additional amount of sodium hydroxide solution is added to the reaction emulsion to maintain the pH, and the necessary molecular chain stopper is also pumped in. Thus, the reaction emulsion containing the additional component is introduced into another reaction coil. After the reaction emulsion has exited the reactor, a polycondensation catalyst is added and the emulsion is pumped through a flow tube to produce a high molecular weight polycarbonate. The emulsion is then separated into its phases in a simple separation vessel. Returning part of the aqueous reaction phase to the first reaction stage,
The remainder is removed and the wastewater is treated. The organic phase is washed in a known manner until the electrolyte is depleted. The polycarbonate is isolated by evaporation of the solvent according to known methods.

The thermoplastic aromatic polycarbonate obtained by the method of the present invention has a weight average molecular weight of 10,000 to 100,000 (for example, 25 ° C. and 100 m ₂ of CH ₂ Cl _2).
(determined after correction by measuring the relative solution viscosity in CH ₂ Cl ₂ at a concentration of 0.5 g / l).

It is processed by ordinary equipment,
Any moldings and products such as films, threads, plates, lamp housings, optical lenses and compact
Discs can be manufactured.

The usual additives such as stabilizers, mold release agents, flame retardants, antistatic agents, fillers, fibers, impact modifiers, etc., are used during or during the process of isolating the polycarbonate obtained according to the invention. Before or during it can be added in the usual amounts for thermoplastic polycarbonates.

The thermoplastic polycarbonates obtained by the process according to the invention are, in a common field for polycarbonates,
It is used industrially, for example, in the electrical field or in the construction industry for the purpose of weight reduction and for optical purposes, in particular in the field of optical and acoustic discs.

[0044]

EXAMPLE 1 88.4 kg / h of bisphenolate solution, 85.2 kg / h of a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 6.4 kg / h of phosgene, 177 kg / h of aqueous reaction phase and 50% Sodium hydroxide solution 2.1
5 kg / h were pumped into a pump circulation reactor with a heat exchanger. The bisphenolate solution contained 15% by weight of bisphenol A and 2 moles of sodium hydroxide per mole of bisphenol A. The concentration of BPA was 5% by weight of bisphenol A based on the amount of aqueous phase introduced.

The temperature was maintained at 28 ° C. by cooling and the average residence time was 6.9 minutes.

[0046] Prior to introduction into the first dwell reactor capable of controlling the ing from agitation and residence time domain heat, the reaction emulsion, methylene chloride 50 parts by weight of chlorobenzene 50 parts by weight of the solvent mixture 5% 3.92 kg of phenol solution
/ H and 0.91 kg / h of 50% sodium hydroxide were added.

The temperature was adjusted to 31.degree. The average residence time was 3.0 minutes.

Then, while adding 3.3 kg / h of a 2% by weight solution of N-ethylpiperidine in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, the reaction emulsion is subjected to another retention reactor having a similar structure. Pumped inside. The temperature was adjusted to 36 ° C. The average residence time was 3.0 minutes.

When the emulsion was observed, it was spontaneously phase-separated after leaving the reactor. In a 1 l measuring beaker, the sample separation time was about 1 minute. The residual water content of the crude polycarbonate solution was 0.27%.

[0050] The aqueous reaction phase OH ^- 0.23%, CO ₃ ^2-
0.41%, phenol 45 ppm and bisphenol A <10 ppm were found. The pH was 13.2.

The catalyst was removed from the crude polycarbonate solution by extraction with an acid according to a known method, and then the electrolyte was removed by washing with water.

The polycarbonate was isolated by evaporation of the solvent in the extruder. In the extruder, a colorant was added to the polycarbonate to counteract the yellow shade and the tinuvin 350 (Ciba Geigy) was UV
Incorporated as stabilizer.

The following data was determined for this polycarbonate: relative viscosity 1.267, saponifiable chlorine <
2 ppm, phenolic OH end groups 90 ppm, sodium <0.5 ppm, transmitted light 89.4%, 0.31% of free tinuvin 350 and total tinuvin 350 content (UV
(Determined by spectroscopy) 0.30%. Within the accuracy of the measurement, the introduction of tinuvin did not occur.

Example 2 The same apparatus arrangement as in Example 1 was used. The following feed streams were introduced: 66.3 kg / h of bisphenolate solution, 85.2 kg / h of a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 6.4 kg / h of phosgene, 199 kg / h of the aqueous reaction phase and 50 1.94 kg / h% sodium hydroxide solution. The bisphenolate solution contained 20% by weight of bisphenol A and 2 moles of sodium hydroxide per mole of bisphenol A. The concentration of BPA was 5% by weight of bisphenol A, based on the aqueous phase introduced.

The temperature was kept at 28 ° C. by cooling. The average residence time was 6.9 minutes.

Before the reaction emulsion enters the first residence reactor, it is added to a solution of 3.92 kg / h and 50% of a 5% phenol solution in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene. Sodium hydroxide solution 0.
83 kg / h were added. The temperature was adjusted to 31 ° C. The residence time was 3.0 minutes.

Next, 50 ml of methylene chloride was added to the reaction emulsion.
Parts by weight of a solvent mixture of 2 parts by weight and 50 parts by weight of chlorobenzene.
3.3 kg / h of a% by weight N-ethylpiperidine solution were added and this was passed into another residence reactor. Temperature 3
Adjusted to 6 ° C. The average residence time was 3.0 minutes.

The emulsion was observed for spontaneous phase separation after exiting the reactor. The separation time of the sample in the 1 l measuring beaker was about 1 minute. The residual water content of the crude polycarbonate solution was 0.25%.

[0059] in the aqueous reaction ^phase, OH - ^0.26%, CO ₃
² 0.58%, phenol 10 ppm, and bisphenol A <10 ppm was found. Its pH is 13.3
Turned out to be.

The phases were processed as in Example 1.

The following data was determined for this polycarbonate: relative viscosity 1.267, saponifiable chlorine <
2 ppm, phenolic OH end groups 70 ppm, sodium <0.5 ppm, transmitted light 89.4%, 0.30% of free tinuvin 350 and total tinuvin 350 content (UV
Within 0.31% of the accuracy of the measurement (determined by spectroscopy), the introduction of tinuvin did not occur.

Example 3 The same apparatus arrangement and the same amount as in Example 1 except that a solvent mixture of 70 parts by weight of methylene chloride and 30 parts by weight of toluene was used instead of the solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene. Raw materials were used.

The temperature in the reactor and the average residence time were determined in Example 1.
And were substantially identical.

After the phase separation, the residual water content in the crude polycarbonate solution was 0.19%. The separation time of the sample in the 1 l measuring beaker was about 1 minute.

[0065] The aqueous reaction ^phase, OH - ^0.23%, CO ₃
² 0.41%, phenol 55 ppm, and bisphenol A <10 ppm was found. Its pH is 13.2
It was. The treatment after spontaneous phase separation was as in Example 1.

The following data was determined for this polycarbonate: relative viscosity 1.264, saponifiable chlorine <
2 ppm, phenolic OH end groups 85 ppm, sodium <0.5 ppm, transmitted light 89.7%, free tinuvin 350 0.30% and total tinuvin 350 content 0.30
%. The introduction of Tinuvin did not occur.

Example 4 The same reactor arrangement and the same amounts of starting materials as in Example 1 were used, except that pure methylene chloride was used instead of the solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene.

The temperatures were substantially the same. The average residence time in the pump circulation reactor was 7.0 minutes and that in the residence reactor was 3.1 minutes each.

After spontaneous phase separation, the residual water content in the crude polycarbonate solution was 0.31%. The separation time of the sample in the 1 l measuring beaker was about 1 minute.

[0070] The aqueous reaction ^phase, OH - ^0.25%, CO ₃
² 0.44%, phenol 45 ppm, and bisphenol A <10 ppm was found. Its pH is 13.4
Turned out to be.

Polycarbonate is obtained by replacing methylene chloride with toluene, and then converting the toluene to German Patent Publication No. 1
Isolated in an extruder by evaporating in an evaporator as described in 920302.

The following data was determined for this polycarbonate: relative viscosity 1.270, saponifiable chlorine <
2 ppm, phenolic OH end groups 50 ppm, sodium <0.5 ppm, transmitted light 89.2%, free tinuvin 350 0.29% and total tinuvin 350 content 0.29
%. The introduction of Tinuvin did not occur.

Example 5 The same reactor arrangement and the same amounts of starting materials as in Example 1 were used, except that pure chlorobenzene was used instead of the solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene. The pump circulation reactor volume was reduced to a shorter residence time. Then, the heat of reaction was not removed so as to obtain the required temperature for dissolving the produced polycarbonate.

The temperature in the pump circulation reactor was 69 ° C. and the average residence time was 2.7 minutes. The temperature in the first residence reactor was 75 ° C and the second was 84 ° C. The average residence time in each reactor was 2.9 minutes.

After the spontaneous phase separation, 0.17% of residual water was found in the crude polycarbonate.

The separation time of the sample in the 1 l measuring beaker was about 1 minute.

[0077] The aqueous reaction phase OH ^- 0.24%, CO ₃ ^2-
0.41%, 40 ppm phenol and <10 ppm bisphenol A were found. The pH was 13.2.

The polycarbonate was isolated as in Example 1.

The following data was determined for this polycarbonate: relative viscosity 1.263, saponifiable chlorine <
2 ppm, 115 ppm phenolic OH end groups, <0.5 ppm sodium, 89.9% transmitted light, 0.32% free tinuvin 350 and 0.3 content of total tinuvin 350
1%. Within the accuracy of the measurement, the introduction of tinuvin did not occur.

[0080] Using raw materials Control 1 except that no return the aqueous reaction phase in Example 1 and the same reactor configuration and the same amount.

The temperature in the pump circulation reactor was 28 ° C. and the average residence time was 13.3 minutes. Data for the first residence reactor: 31 ° C and 5.8 minutes; data for the second reactor: 36 ° C and 5.7 minutes.

The residual water content of the crude polycarbonate solution after the phase separation was 9.4%. This value was not substantially reduced even after the sample was left for 8 hours. The sample separation time in a 1 l measuring beaker was 13 minutes.

[0083] The aqueous reaction phase OH ^- 0.21%, CO ₃ ^2-
0.48%, 345 ppm of phenol and 770 ppm of bisphenol A were found. pH was 13.0.

The polycarbonate was separated as in Example 1.

The following data were determined for the polycarbonate: relative viscosity 1.224, saponifiable chlorine <2.
ppm, phenolic OH end groups 830 ppm, sodium 3.4 ppm. Poor analytical data indicated that no additives were introduced.

Control 2 This example was the same as Control 1 except that the amount of phosgene was increased to 7.0 kg / h. The amount of sodium hydroxide solution for the pump circulation reactor is 3.47 kg / h and for the first residence reactor its amount is 1.49 kg / h.
It was time.

The temperature and average residence time were the same as in Control Example 1.

The residual water content of the crude polycarbonate solution after phase separation was 2.9%. This value was not substantially reduced even after the sample was left for 8 hours. The separation time of the sample in a 1 l measuring beaker was 8 minutes.

[0089] The aqueous reaction phase OH ^- 0.20%, CO ₃ ^2-
0.87%, 245 ppm phenol and 230 ppm bisphenol A were found. The pH was 13.2.

The polycarbonate was separated as in Example 1.

The following data were determined for the polycarbonate: relative viscosity 1.273, saponifiable chlorine <2.
ppm, 190 ppm phenolic OH end groups, 1.1 ppm sodium, 88.5% light transmission, 0.16% of free tinuvin 350 and 0.3 content of total tinuvin 350
2%, Tinuvin was partially introduced (0.16%).

Control 3 The same reactor arrangement as in Example 1 was used. The following feed streams were introduced: 88.4 kg / h of a bisphenolate solution, 85.2 kg / h of a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 6.4 kg / h of phosgene, 177 kg / h of water and 50% water Sodium oxide solution 3.6
0 kg / hour. Bisphenolate solution is bisphenol A
It contained 15% by weight and 2 moles of sodium hydroxide per mole of bisphenol A.

The temperature was maintained at 28 ° C. by cooling. The average residence time was 6.6 minutes.

To the reaction emulsion, before it enters the first residence reactor, a 3.9% phenol solution in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 3.9.
2 kg / h and 1.54 k of 50% sodium hydroxide solution
g / h were added. The temperature was 31 ° C. and the average residence time was 2.9 minutes.

Then, while adding 3.3 kg / h of a 2% by weight solution of N-ethylpiperidine in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, the reaction emulsion is subjected to another retention reaction of the same structure. It was pumped into the vessel. The temperature was 36 ° C. and the residence time was 2.9 minutes.

The residual water content of the crude polycarbonate solution after the phase separation was 5.3%. This value did not substantially decrease even after the sample had been left for 8 hours. The sample separation time in a 1 l measuring beaker was 5 minutes.

[0097] The aqueous reaction phase OH ^- 0.20%, CO ₃ ^2-
0.16%, 295 ppm phenol and 630 ppm bisphenol A were found. pH was 13.0.

The following data were determined for the polycarbonate: 1.312 relative viscosity, <2 saponifiable chlorine.
ppm, phenolic OH end groups 610 ppm, sodium 0.5 ppm. No additives were introduced due to this end group.

Control Example 4 The same reactor arrangement as in Example 1 was used. The following feed streams were introduced: 88.4 kg / h of bisphenolate solution, 85.2 kg / h of a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 7.0 kg / h of phosgene, 177 kg / h of water and 50% water Sodium oxide solution 4.9
4 kg / hour. Bisphenolate solution is bisphenol A
It contained 15% by weight and 2 moles of sodium hydroxide per mole of bisphenol A.

The temperature was maintained at 28 ° C. by cooling. The average residence time was 6.6 minutes.

Before the reaction emulsion enters the first residence reactor, a 3.9% phenol solution in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, 3.9.
2kg / h and 2.12k of 50% sodium hydroxide solution
g / h were added. The temperature was 31 ° C. and the average residence time was 2.9 minutes.

Then, while adding 3.3 kg / h of a 2% by weight solution of N-ethylpiperidine in a solvent mixture of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene, the reaction emulsion is subjected to another retention reaction of the same structure. It was pumped into the vessel. The temperature was 36 ° C. and the residence time was 2.9 minutes.

The residual water content of the crude polycarbonate solution after the phase separation was 0.22%. The separation time of the sample in the 1 l measuring beaker was about 1 minute.

[0104] The aqueous reaction ^phase, OH - ^0.22%, CO ₃
² 0.29%, was found phenol 260ppm and bisphenol A 370 ppm. The pH was found to be 13.3.

The following data was determined for this polycarbonate: relative viscosity 1.347, saponifiable chlorine <2 ppm, phenolic OH end groups 285 ppm, sodium 0.5 ppm, light transmission 89.3%, free 0.30% of Tinuvin 350 and a total Tinuvin content of 0.31
%. No introduction of tinuvin occurred within the accuracy of the measurement.

The features and aspects of the present invention were as follows: From a raw material containing phosgene, diphenol, a molecular chain terminator and an optional branching agent, an aqueous alkali metal salt solution of diphenol is dissolved in a solvent or solvent mixture which dissolves aromatic oligocarbonate and aromatic polycarbonate and is not itself water-miscible. The production of thermoplastic aromatic polycarbonates by continuous phase interfacial polycondensation, which is phosgenated with a polycondensation catalyst and three reactors arranged in series at a pH value of 8 to 14 in the presence of A portion of the aqueous reaction phase obtained after completion of the reaction is returned to the phosgenation reactor together with the feed in such an amount that an oil / water emulsion is formed directly and is maintained in the three reactors during the reaction. A process for producing polycarbonate by the continuous phase interfacial polycondensation.

2. a) reacting an aqueous alkali metal solution of diphenol in the first reactor with phosgene by adding monophenol in the presence of an organic solvent; b) allowing a time difference between the returned aqueous reaction phase and the further alkali metal liquid. C) passing the intermediate product obtained to be reacted in the second reactor, optionally with addition of monophenol and an additional amount of sodium hydroxide solution, and d) this latter The process of claim 1, wherein the intermediate product is contacted in the presence of a polycondensation catalyst.

3. The concentration of diphenol in the aqueous alkali metal salt solution is 10 to 10 based on the aqueous alkali metal salt solution.
The method of 1 above, which is 40% by weight.

4. The process of claim 1 comprising recirculating the aqueous reaction phase in an amount such that the concentration of diphenol based on the total aqueous phase is 2.5 to 25% by weight.

5. The process of claim 1 comprising recirculating the aqueous reaction phase in an amount such that the concentration of diphenol based on the total aqueous phase is 2.5 to 15% by weight.

6. The aqueous reaction phase to be recirculated must be cooled to such an extent that the lowest boiling solvent of the solvent used or of the solvent mixture used does not reach the boiling point under normal pressure in the three reactors without further cooling. The method of claim 1 returned.

7. The process of claim 1 wherein the solvent or solvent mixture used has a boiling point above the temperature at which it is established in the reaction mixture without pre-cooling of the recirculated aqueous reaction phase, and thus cooling can generally be omitted.

8. The residence time is 10 seconds to 30 minutes for the first reaction stage, 1 to 30 minutes for the second reaction stage,
And the method of the above 1, which is for 2 to 30 minutes for the third reaction stage.

9. Any of the three reaction stage reactors is a flow tube, or one pump circulation reactor is used as the reactor for the first reaction stage and two flow tubes are used for two other The process of claim 1 wherein the reaction stage is used or two pumped circulation reactors are used for the first two reaction stages and one flow tube is used for the third reaction stage.

────────────────────────────────────────────────── 72 Continuation of the front page (72) Inventor Wolfgang Helich Germany Day 51465 Bergisch Jugrad-Bazha Romersia Idasi Jutrase 43 (56) Reference US Patent 5015720 (US, A) US Patent 4737573 (US, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 64/00-64/42

Claims (2)

(57) [Claims] 1. An aqueous alkali metal salt solution of diphenol is dissolved from a raw material containing phosgene, diphenol, a molecular chain terminator and an optional branching agent by dissolving aromatic oligocarbonate and aromatic polycarbonate and mixing itself with water. 8-14 in the presence of a solvent or solvent mixture
At the H value, for the production of thermoplastic aromatic polycarbonates by continuous phase interfacial polycondensation, phosgenating using a polycondensation catalyst and three reactors arranged in series,
A portion of the aqueous reaction phase obtained after completion of the reaction is returned to the phosgenation reactor together with the feed in such an amount that an oil / water emulsion is formed directly and is maintained in the three reactors during the reaction. A process for producing polycarbonate by the continuous phase interfacial polycondensation. 2. a) In a first reactor, an aqueous alkali metal solution of diphenol is reacted with phosgene by the addition of monophenol in the presence of an organic solvent; b) The returned aqueous reaction phase and further alkali Introducing the metal liquid at intervals, c) passing the intermediate product obtained for reaction in the second reactor, optionally with addition of monophenol and an additional amount of sodium hydroxide solution, and d) The process of claim 1 wherein said latter intermediate product is condensed in the presence of a polycondensation catalyst.