JPH05222183A - Production of polycarbonate - Google Patents

Abstract

PURPOSE: To obtain a highly uniform polycarbonate by adding an alkali hydroxide soln. to the part on the upstream side of a heat exchanger to hold the same for a specific stagnation time and thereafter adding a chain stopper to the soln. to react phosgene, a diphenol, the chain stopper and a catalyst.

CONSTITUTION: After an alkali hydroxide soln. is added to the part on the upstream side of a heat exchanger having a circulating loop to be stagnated in a reaction container for 2-15 min, a chain stopper and the optionally additional alkali hydroxide soln. are added and, after 2-15 min, a catalyst and the optionally additional alkali hydroxide soln. are added. Next, an org. phase composed of a phosgene-containing polycarbonate soln. and an aq. phase composed of a mixture of water, the alkali hydroxide soln. and a phenolic component are heated to 60°C or lower in the heat exchanger to form an emulsion which is, in turn, stagnated for 2-15 min to be moved continuously through the reaction container and this emulsion is introduced into a tubular reactor to be passed therethrough over 20-30 min to be converted to an oil in water type emulsion to react phosgen and the diphenol.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

The two-phase interfacial process has been used successfully for the production of polycarbonate on an industrial scale for many years. This method allows the production of thermoplastic polycarbonates for many applications. Due to the varying high demands placed on the processing of polycarbonate granules (extremely short cycle times and the large number of parts per cycle in the case of injection molding machines of complex design)
The purity and homogeneity of polycarbonate is required to meet high standards.

One of the important factors for obtaining a high quality polycarbonate is to ensure that the content of monocarbonate is as low as possible. One mole of monocarbonate is formed from two moles of chain terminator and one mole of phosgene. For high monocarbonate content,
The use of high amounts of phosgene is required. Also, since monocarbonate represents a low molecular weight component contained in high molecular weight polycarbonate, it has a detrimental effect on subsequent processing (white deposit formation, reduction of parts per cycle and wear of molding equipment). Have.

Several patent applications, patents and publications
It suggests ways to avoid high monocarbonate contents or describes possible reductions in phosgene usage. In particular, here are some patent applications (eg DOS-23 05 144, DOS-23 53 939, EP-02 82 54).
6, EP-02 63 432, DOS-27 25 967, EP-03 06838
-A2, EP-03 39 503-A2, EP-03 04 691-A2, WO
88/01996, US-4447 655, AT-341 225, EP-02 62
695-A1, EP-A-00 36 080, EP-A-0010 602, E
P-A-00 78 943, DOS-19 43 803 and EP-A-0
2 51 586) as a typical EP-03 69 422-A2
Can be mentioned. According to EP-03 69 422-A2
The amount of monocarbonate used to make the polycarbonate is kept low by the optimal timing of introduction of the chain terminator. Particular mention is made of the importance of using the heat of reaction as a criterion for the subsequent introduction of chain terminators.
Since the heat of reaction does not dissipate during phosgenation and oligomer formation, the optimum time point for metering in the chain terminator can be evaluated by the thermal effect. In addition, the chain terminator is added only after the oligomer formation is essentially complete. As one might expect, the formation of monocarbonates is almost completely avoided in this way. Other quality determinants, which are also very important for reducing cycle times and for obtaining high space / time yields in processing polycarbonate granules in injection molding equipment, are: uniformity of polycarbonate granules. Gender must be constantly maintained high. That is, its relative viscosity must be highly constant throughout the manufacturing process (relative viscosity is 0.5 g of polycarbonate / 10 methylene chloride).
Measure at T = 25 ° C in 0 ml of solution). In a continuous production process, the deviation of the relative solution viscosity (standard deviation) of the individual production batches should not exceed 0.003, ie a relative viscosity of, for example, 1.28 (a weight of about 27,000 g / mol for Makrolon). If the relative viscosities of the individual granules of the polycarbonate having an average molecular weight Mw) are relatively long, for example only varying in the "viscosity range" of 1.277 to 1.283 over the production period which requires 100 tons, Polycarbonates can be considered to exhibit a high degree of uniformity.

For example, for the production of compact discs,
The injection molding variables (raw material temperature, injection pressure, residence time, etc.) of the injection molding apparatus are usually adjusted only once. Fine tuning of processing equipment during high volume production of injection molded parts is undesirable because it involves high labor costs and cycle times, i.e. extended molding time. Therefore, it is extremely important that the polycarbonate granules exhibit a high degree of uniformity in order to avoid the need for reconditioning of the processing equipment.

Suggestions for the production of polycarbonate by the continuous two-phase interfacial process, in which the polycarbonate exhibits a consistently high homogeneity throughout the production process, ie throughout the polymer reaction itself, can be found elsewhere in the literature. I can't.

Surprisingly, the use of an equipment system which comprises a heat exchanger with a circulation loop, a reaction vessel and a residence tube as a reactor configuration makes it possible to adjust a particular emulsion ratio in the equipment system. It has been found that by doing so and by introducing a sodium hydroxide solution, a chain terminator and a catalyst in a very specific way, a highly homogeneous polycarbonate can be obtained in a continuous two-phase interfacial process.

The average residence time of a heat exchanger having a circulation loop, which includes a heat exchanger having a circulation loop, and a reaction vessel and a residence tube including a residence tube is incorporated.
After introducing the alkali hydroxide solution into the system for 2 to 15 minutes, at least 2 more minutes before adding the chain terminator and any additional alkali hydroxide solution.
A high quality polycarbonate is produced if the emulsion is passed through the reactor, preferably with a residence time of 2 to 15 minutes, and after a further 2 to 15 minutes the catalyst and optionally additional alkali hydroxide solution are added. It was found possible.

Therefore, the present invention relates to 1. 1. Add additional alkali hydroxide solution upstream of the heat exchanger, At least 2 minutes in the reaction vessel, preferably 2
Use a dwell time of 15 to 15 minutes. Then only the solution of chain stopper and optionally additional alkali hydroxide is added, Aqueous / alkaline phase from diphenols, phosgene, chain terminators, catalysts and optionally branching agents, characterized in that after a further 2 to 15 minutes the catalyst and optionally a solution of additional alkali hydroxide is added. The following process steps in a mixture of a and an organic solvent phase: In a system of equipment comprising a heat exchanger with a circulation loop, optionally with the aid of a mixing element, an organic phase which is a suitable solvent for polycarbonate and which already contains phosgene, and water and water. 1. A solution of alkali oxide and a mixture of phenolic components and an aqueous phase consisting of are mixed continuously, where A water-in-oil emulsion is formed in the system of the apparatus including a heat exchanger having a circulation loop, and with the aid of the heat exchanger, 60 ° C or less, preferably 55 ° C-25 ° C in the circulation loop.
And a mean residence time of at least 2 minutes, preferably 2 to 15 minutes in a system of equipment comprising a heat exchanger with a circulation loop to produce an emulsion via the reaction vessel. Continuously move, 3. This emulsion is then passed through a tubular reactor equipped with a mixing zone and a retention zone using a total residence time of 2 to 30 minutes, during which the emulsion becomes an oil-in-water emulsion. The present invention relates to a continuous production method of polycarbonate by a two-phase interface method including conversion.

The method according to the invention guarantees in particular a highly constant relative solution viscosity.

The method according to the invention also provides good phase separation.

A particularly preferred embodiment is a heat exchanger having a circulation loop, a reaction vessel and a heat exchanger arranged downstream thereof.
A system comprising a tubular reactor consisting of 4 individual parts, wherein the chain stopper and sodium hydroxide solution are added upstream of the first part of the tubular reactor and the catalyst upstream of the second part. Added. In this embodiment, the residence time in the system including the heat exchanger with the circulation loop is 2
Minutes to 15 minutes, 2 to 15 minutes in the reaction vessel
Minutes, 1 to 15 minutes in the first part of the tubular reactor and 1 to 15 minutes in the second part of the tubular reactor.

The residence time used between the introduction of sodium hydroxide upstream of the heat exchanger and the introduction of the chain terminator into the first part of the tubular reactor is between 2 and 15 minutes, therefore It substantially corresponds to the residence time in the reaction vessel.

Suitable diphenols have a Z in the formula 6
To formula H which is an aromatic radical having 45 C atoms
O-Z-OH, which is 1 or 2
It may contain one or more aromatic rings, may be substituted, and may contain an aliphatic group or a cycloaliphatic group or a hetero atom as a connecting bond.

Examples are dihydroxydiphenyl, bis- (hydroxyphenyl) -alkanes, bis- (hydroxyphenyl) -cycloalkanes, bis- (hydroxyphenyl) -sulfides, bis- (hydroxyphenyl) -ethers and their ring alkyls. And ring-halogenated compounds.

These and other suitable diphenols are described, for example, in US-PS 3028365, 4982014, 299983.
5,3148172,3275601,2991273,3271367,3062781,29
70131 and 2999846 with DOS 1570703, 2063050,
2063052, 2211956, French Patent No. 1561518,
Further, it is described in DE-OS 3833953.

The preferred diphenols are 2,2-bis- (4-hydroxyphenyl) -propane (bisphenol A) and 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane (HIP -Bisphenol).

It should be emphasized that the method according to the invention can be used for virtually all known diphenols.

Suitable chain terminators and branching agents are known from the literature. Some of these are, for example, DE-
It is described in OS 3833953. Preferred chain terminators are phenol, cumylphenol, isooctylphenol and p-tert-butylphenol. Preferred branching agents are trisphenol and tetraphenol, and 3,3-bis- (3-methyl-4-hydroxyphenyl) -2-oxo-2.3-dihydroindole.

A sodium hydroxide solution or a potassium hydroxide solution is used as the alkali hydroxide solution, but it is also possible to use an alkaline earth metal hydroxide solution. Sodium hydroxide solution is preferred.

Suitable catalysts are essentially all the known catalysts for the production of polycarbonates by the two-phase interfacial method. N-ethylpiperidine and triethylamine are preferred. The organic phase contains a solvent or a mixture of solvents in which the polycarbonate can be dissolved. A suitable solvent is about
All known solvents and mixtures of solvents which are capable of dissolving polycarbonate to a degree of at least 5% by weight at a temperature of 20 ° C.

Preferred solvents are methylene chloride, toluene and monochlorobenzene, with methylene chloride and mixtures of methylene chloride and monochlorobenzene in a ratio of 20:80 parts by weight to 75:25 parts by weight being particularly preferred.

The reaction vessel may optionally contain suitable mixing means for stabilizing the reaction solution / emulsion.

PH values of 10 to 14, preferably 10.5 to 13.5, are used throughout the reaction. This is done by first adding the amount of alkali hydroxide solution required to dissolve the diphenol, then adding a first additional amount of alkali hydroxide solution upstream of the heat exchanger,
Is added with an additional amount of alkali hydroxide solution with a chain terminator or with a catalyst.

According to the process according to the invention, polycarbonates are obtained which have easily reproducible relative viscosities, in particular constant viscosities throughout the production, even in continuous production processes. A molecular weight Mw (weight average) of 10,000 to 100,000 is obtained.

The polycarbonates can be processed by known methods to produce the desired moldings, and the additives commonly used for thermoplastic polycarbonates, such as stabilizers, mold release agents, flame retardants, fillers. The agent or glass fiber can be added before or during processing.

The polycarbonates obtainable by the process according to the invention are known in a known manner in the form of moldings of any type, for example in the form of sheets, films or wires, for example in the automotive sector or in the optical field, and Especially in the form of a compact disc, it can be used commercially.

[0027]

Example 1 Alkaline bisphenol A solution containing 15% by weight of bisphenol A and 2 mol of sodium solution per mol of bisphenol A 87.0
kg / h via a T-type coupler upstream of the pump
Introduced into a reactor containing a heat exchanger with a circulation loop, phosgene 6.9 kg / h dissolved in a solvent of 75.0 kg / h consisting of 50 parts by weight of methylene chloride and 50 parts by weight of chlorobenzene was added to another T- Introduced via a mold coupler. While pumping in 1.50 kg / h of a 50% sodium hydroxide solution, the reaction mixture is pumped through the heat exchanger and back into the pump, where the above component streams are added. The average residence time in the reactor including the heat exchanger with circulation loop is 7.0 minutes. The temperature is 35 ° C. The pH value is 11.2.

A portion of the reaction emulsion corresponding to the volumetric flow of the raw materials introduced is removed from the branch pipe via a T-type connector upstream of the feed point of bisphenol A and phosgene and the reaction vessel is opened. Let it pass. The average residence time is 3.2 minutes.

Then, a 50% sodium hydroxide solution 3.4
kg / h and 5.0% p-isooctylphenol dissolved in a solvent consisting of 50 parts by weight methylene chloride and 50 parts by weight chlorobenzene p-isooctylphenol solution 9.7 kg / h is added to the emulsion. ..

The residence time of the reaction emulsion in the tubular reactor is
6.2 minutes. Without cooling, the temperature rises to 38 ° C.

Then, 50 parts by weight of methylene chloride and 50 parts by weight of
5 parts by weight dissolved in a solvent consisting of chlorobenzene 5
% N-Ethylpiperidine solution 1.3 kg / h are added and the reaction emulsion is pumped through another tubular reactor. The average residence time in this tubular reactor is 12.1
Minutes. Measure the pH value of 13.4.

The emulsion is then placed in a heat exchanger at 42 ° C.
To 30 ° C and separate the two phases in a separation vessel. The crude polycarbonate solution is washed in a known manner until free of electrolytes, the solvent is removed in an evaporator and the polycarbonate is isolated via an extruder.

All these steps are carried out continuously. The relative viscosity of the resulting polycarbonate is measured at hourly intervals. The results for relative viscosity over 24 hours (which constitutes the longer term part of the operation) are: Mean value: 1.254 Highest value: 1.256 Lowest value: 1.250 Standard deviation: 0.0016.

Front page continued (72) Inventor Ube Fuchs Germany Day 4234 Alpen am Mariensteinft 30 (72) Inventor Jürgen Heuser Germany Federal Day 4150 Kleifert 1 Mink Beek 29 Ar (72) Inventor Jürgen・ Kirsyu Germany Day 5090 Lef Erkusen 1 ・ Fuel Klinger Shiyu Trase 20 (72) Inventor Guyunter Beimans Germany Day 5090 Lef Erkusen 1 ・ Kernassyu Trase 5 (72) Inventor Jürgen Kaderka Federal Republic of Germany Day 4150 Klefelt 11 Karl-Dowisberg-Shutlerse 28

Claims (1)

[Claims] 1. 1. Add additional alkali hydroxide solution upstream of the heat exchanger, At least 2 minutes in the reaction vessel, preferably 2
Use a dwell time of 15 to 15 minutes; Then only the solution of chain stopper and optionally additional alkali hydroxide is added, After an additional 2 to 15 minutes, an aqueous alkaline phase from the diphenol, phosgene, chain terminator, catalyst and optionally branching agent, characterized in that a solution of catalyst and optionally additional alkali hydroxide is added. The following process steps in a mixture with an organic solvent phase: In a system of equipment comprising a heat exchanger with a circulation loop, optionally with the aid of a mixing element, an organic phase which is a suitable solvent for polycarbonate and which already contains phosgene, water and water. 1. A solution of alkali oxide and a mixture of phenolic components and an aqueous phase consisting of are mixed continuously, where A water-in-oil emulsion is formed in the system of the apparatus including a heat exchanger having a circulation loop, and the heat exchanger is used to generate a temperature of 60 ° C. or less in the circulation loop. At least 2 in the system of equipment, including heat exchangers
2. Continuously move the emulsion through the reaction vessel using an average residence time of minutes; This emulsion is then passed through a tubular reactor equipped with a mixing zone and a retention zone using a total residence time of 2 to 30 minutes, during which the emulsion becomes an oil-in-water emulsion. A continuous method for producing a polycarbonate by a two-phase interfacial method including conversion.