JPH06329782A - Production of polycarbonate - Google Patents

Abstract

PURPOSE: To produce a thermoplastic aromatic polycarbonate which is free from deterioration of quality in good reproducibility by re-using the catalyst recovered from the crude polycarbonate solution by a specified method in producing the polycarbonate from COCl₂, a diphenol, a chain terminator, etc., by a specified method.

CONSTITUTION: There is provided a process for producing a polycarbonate from COCl₂, a diphenol (e.g. bisphenol), a chain terminator (e.g. phenol) and optionally a branching agent by interfacial condensation comprising phosgenating an aqueous solution of an alkali metal of the diphenol in the presence of a solvent (mixture) which dissolves the aromatic oligocarbonate and the polycarbonate and which itself is not miscible with water (e.g. methylene chloride and chlorobezene) by using a polycondensation catalyst (e.g. N-ethylpiperidine) at a pH of 8-14 in a varied phase ratio, wherein the catalyst extracted by reaction from the crude polycarbonate solution directly, namely, without isolation or purification, is re-used.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

The present invention dissolves an aqueous solution of an alkali metal salt of a diphenol, an aromatic oligocarbonate and a polycarbonate from phosgene, a diphenol, a chain terminator, and an optional branching agent, and is immiscible with water itself. Thermoplasticity in interfacial condensation by phosgenating in the presence of a solvent, or a solvent mixture, with a polycondensation catalyst at a pH value of 8 to 14 in two or more process steps with varying phase ratios. In the process for the production of aromatic polycarbonates, the catalysts which have been reactively extracted with acid from the crude polycarbonate solution can be reused directly, ie without isolation or purification, and the catalysts lost can be supplemented with pure catalytic material at any time. And a method for producing a thermoplastic aromatic polycarbonate.

The use of N-alkyl substituted aliphatic and cycloaliphatic amines has been extensively described in the literature [see European Patent (EP) 0000 753].

The catalyst, regardless of the method of preparation used, must be quantitatively completely separated from the polycarbonate solution before the polycarbonate is isolated. If the catalyst remains, there is always a thermal process in the production of polymer granules or final parts, which inevitably leads to deterioration of quality.

In standard practice, the reaction emulsion is phase separated and the crude polycarbonate solution is acid extracted to chemically convert the catalyst to a water soluble compound followed by a water wash.

The entire aqueous phase is collected and reprocessed. The reprocessing consists of a purification stage and a final distillation stage. Loss of the recovered purified catalyst makes up for new catalyst. The catalyst is then reused in the amount required for the polycondensation reaction.

It has been surprisingly discovered that the polycondensation reaction can be reproducibly carried out by returning the extracted water directly to the reaction without a purification step. It was observed that the residence time did not change in particular. The phase separation is the same or improved. Unexpectedly, direct reuse of the catalyst without a purification step did not result in tailing and quality degradation. Furthermore, it has been discovered that catalyst losses are less than in conventional catalyst recovery.

In a preferred embodiment of the invention, the multi-step washing of the crude polycarbonate solution is carried out by flowing water countercurrently and adding a high concentration of acid to the wash water obtained before entering the catalyst extraction step. And the wash water obtained from the extraction step is used as a catalyst solution for the direct polycondensation reaction according to the invention. It is particularly advantageous that it is not necessary to purify the waste wash water containing the catalyst residues.

A suitable washing device consists of a mixer / separator, for example a combination of a stirred vessel and a separating tank or a centrifugal mixer and a separator. A static mixer has been found to be a particularly suitable device for mixing acids.

For the production of high molecular weight polycarbonate,
The diphenols which can be used in the process according to the invention are diphenols which form water-soluble alkali metal salts with alkali metal hydroxides, such as sodium or potassium hydroxide. Alkaline earth metal hydroxides can also be used. These requirements are met by virtually all known diphenols.

Preferred diphenols have the general formula: HO-
Corresponding to Z-OH, Z represents an aromatic nucleus which may be substituted with one or more different substituents. In addition to hydrogen, chlorine and bromine, aliphatic or alicyclic groups are suitable substituents. Furthermore, between the two aromatic nuclei,
There may be aliphatic or alicyclic groups or bridging groups which may contain heteroatoms. For example, hydroquinone, resorcinol, dihydroxydiphenol, bis- (hydroxyphenyl) -alkane, bis- (hydroxyphenyl) -cycloalkane, bis- (hydroxyphenyl) -sulfide, bis- (hydroxyphenyl) -ether, bis- (hydroxy) Phenyl) -ketone, bis- (hydroxyphenyl) -sulfone, bis- (hydroxyphenyl) -sulfoxide, 1,1'-bis- (hydroxyphenyl)-
Diisopropylbenzenes and their nuclear alkylation,
Alternatively, it is a nuclear halogenated compound.

These and other diphenols are
For example, US Patent Specification (US-PSS) Nos. 4,982,014 and 3,0
28,365, 2,999,835, 3,148,172, 3,275,
No. 601, No. 2,991,273, No. 3,271,367, No. 3,062,78
1, 2,970,131, and 2,999,846, German Patent Publication (DE-OSS) 1 570 703, 2 063 050
No. 2,063 052, and No. 2 211 956, and French Patent Specification (FR-PS) No. 1 561 518.

A particularly preferred diphenol is 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 amounts and types of chain terminators known from the literature and optionally branching agents are used before, during or after the phosgenation, but before the catalytic formation of the high molecular weight polycarbonate. , Can be added to diphenols. Suitable chain terminators are the known monophenols, for example phenol itself, C
₁ -C ₁₀ - alkyl phenols, for example p-tert, - butylphenol, and p- cresol, and halo phenols, such as p- chlorophenol and 2,4,6 chromatography tribromophenol. Preferred chain terminators are phenol, cumylphenol, isooctylphenol and
It is p-tert.-butylphenol.

Suitable branching agents are those having three or four, or four or more functional groups, especially three or three.
It is a branching agent having one or more phenolic hydroxyl groups. The branching agent must be used in known amounts, based on the diphenol used together, ie from 0.05 to 2 mol%.

Some of the branching agents containing three or more phenolic hydroxyl groups which can be used in the present invention are, for example, 2,4-bis- (4-hydroxyphenylisopropyl) -phenol, 2,6- Bis- (2'-hydroxy-5'-methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) propane, and 1,4-bis- (4 There is 4,4'-dihydroxytriphenylmethyl) benzene. Some other trifunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride, and 3,3-bis- (4-hydroxyphenyl) -2-oxo-2,3-dihydro. Indole,
And 3,3-bis- (4-hydroxy-3-methylphenyl) -2-
There is oxo-2,3-dihydroindole.

Suitable solvents are any solvents which dissolve the oligocarbonates and polycarbonates under the reaction temperature and pressure applied and are substantially immiscible (in the sense of solution) with water. Chlorinated hydrocarbons such as methylene chloride or chlorobenzene are preferably used.
These solvents can be used individually or as a mixture of various compositions. If chlorobenzene itself is used, higher process temperatures should be applied during the reaction and washing steps, which will give a polycarbonate-chlorobenzene solution of industrially useful concentration. Furthermore, benzene homologues can also be used as solvents. A preferred solvent combination for industrially important 2,2-bis- (4-hydroxyphenyl) -propane-based polycarbonates is a mixture of methylene chloride and toluene, which is the whole step of the manufacturing process. Can be used in. The polycarbonate concentration in the solution containing the above solvent is 5 to 30%.

The process conditions and reaction vessels of the two-phase interface method according to the invention are known in principle.

Suitable reactors are, for example, recirculating reactors or flow tubes with a mixing zone and a stagnant zone, stirring reactors can also be used.

The reaction temperature is generally lower than the boiling point of the solvent used. Higher temperatures can be applied under pressure at any time. The temperature range is 10 ° C to 90 ° C, preferably 20 ° C to 70 ° C. The reaction time depends on the reactor used, but is for a few seconds, for example between 10 seconds and 30 minutes.

The pH value of the interfacial method is known from the literature, for example 8 to 14, preferably 10 to 13.
It is 5.

Among the numerous condensation catalysts described for interfacial processes, trialkylamines such as triethylamine, tripropylamine, tributylamine, dipropylmethylamine, and benzyldimethylamine;
And N-ethylpyrrolidine, N-ethylpiperidine, N
-Ethylmorpholine, N-isopropylpiperidine or N-isopropylmorpholine are of particular interest. Triethylamine and N-ethylpiperidine are particularly suitable.

The production process can be carried out continuously or discontinuously, preferably continuously in two or three stages.

Using fresh catalyst in an amount of 0.01 mol% to 10 mol%, preferably 0.05 mol% to 5 mol%, based on the diphenol used, or the aqueous catalyst extraction solution stored in the previous operation. , The continuous manufacturing method of the present invention is started. The catalyst in the extraction solution is present in salt form therein,
Its concentration is from 0.001% to 4% by weight, preferably from 0.01% to 2% by weight.

The amount of catalyst used in the form of the extraction solution for the production of the polycarbonate is once again calculated on the basis of the amount of diphenol, only 0.01 mol% to 10%.
It is mol%, preferably 0.05 mol% to 5 mol%.

After starting the continuous process, the catalyst accumulates again in the form of an extraction solution and is reused for polycarbonate production. As for the loss of the catalyst, the pure catalyst is replenished by the necessary amount.

When the process is carried out discontinuously, the catalyst extraction solution is prepared in the first reaction and stored for the next reaction.

The amount of catalyst used is again 0.01 mol% to 10 mol%, preferably 0.05 mol% to 5 mol%, based on diphenol per reaction.

Observing changes in the continuous method in advance,
It is applied to the catalyst concentration in the extraction solution to compensate for its loss.

Suitable acids for catalytic extraction are, for example, hydrochloric acid, sulfuric acid, phosphoric acid, and organic acids such as acetic acid or formic acid.

HCl is preferred.

Therefore, the catalyst salt in the extraction solution used in the present invention was quantified for its anion, especially by the specific acid used in the extraction.

The thermoplastic aromatic polycarbonate obtained by the process of the present invention comprises 10,000 to 100,000.
Weight average molecular weight Mw in the range 0 (determined, for example, by measuring relative viscosity at a temperature of 25 ° C. and then 0.5 g concentration in 100 ml of methylene chloride after precorrection).
Can have

The polycarbonate can be processed in standard equipment to form moldings and products of all kinds, such as films, fibers, sheets, lamp housings, optical lenses, and compact discs.

The usual additives such as stabilizers, mold release agents, flame retardants, antistatic agents, fillers, fibers, impact modifiers, etc., in the amounts customarily used in thermoplastic polycarbonates, can be used according to the invention. It can be added during the isolation of the polycarbonate obtained in step 1, or before or during processing.

The thermoplastic polycarbonates obtained according to the invention are used in the typical applications of polycarbonates, for example in the electrical sector, or in the architectural, lighting and optical sector, in particular optical discs and audio discs.

[0036]

Example: 8 wt. Kg of 88.5 kg / h of an equimolar amount of sodium hydroxide in a 15 wt% concentration aqueous bisphenol solution, 3.9 kg of methylene chloride and chlorobenzene 1: 1 mixed solvent with 5 wt. % Dissolved solution, 7.0 kg phosgene, 85 kg 1: 1 mixed solvent of methylene chloride and chlorobenzene, and 3.
47 kg of 50% sodium hydroxide solution is pumped into the recirculation reactor. The temperature is 28 using a heat exchanger.
Adjusted to ° C, the average residence time is 13.8 minutes.

Per hour, 1.49 kg of 50% sodium hydroxide solution and 3.3 kg of 2% N-ethylpiperidine solution are added to the reaction emulsion, which is temperature-controlled and consists of a mixing zone and a retention zone. Add before entering the reactor. The temperature is adjusted to 36 ° C. The average residence time is 6 minutes.

After leaving the reactor, the phases are separated in a separation tank.

The reaction water phase is 0.25% OH ⁻ and 0.8.
3% CO ₃ ^- of it is found to contain ions.

The crude polycarbonate solution is extracted with dilute hydrochloric acid in four separators arranged in tandem to remove the catalyst and washed with water until free of electrolyte. Washing is carried out countercurrently. The amount of fresh water used first is 10 1 / h
Then, it is introduced into the mixing chamber of the third separator and separated by the fourth separator. The accumulated waste water is introduced into the mixing chamber of the second separator and separated in the third separator. The water accumulated there is introduced into the mixing chamber of the first separator,
Separated in the second separator. The wastewater of the second separator has a pH of 3.4. 0.23 kg of 30% strength hydrochloric acid are added to the waste water thus accumulated and are pumped for separation into the first separating device together with the crude polycarbonate solution from the separating tank and subsequently into the static mixer.

The polycarbonate is isolated from the washed polycarbonate solution by evaporating the solvent in an evaporator and passing through an extruder. The polycarbonate obtained has a relative viscosity of 1.291; saponifiable chlorine: <2 ppm; phenolic OH end groups: 145 ppm; sodium: <0.5 p.
pm; yellowness index: 2.1.

After the above steps were operated for 5 hours, the operation of the present invention was switched to. At the end, all accumulated acidic wastewater except N-ethylpiperidine solution is introduced before the entrance to the residence reactor. The amount of sodium hydroxide was 1.49 kg / h to 1.7 to maintain the alkalinity in the residence reactor.
Must be increased to kg / h. Reaction water phase is 0.25
It is found to contain ions of% OH ⁻ and 0.74% CO ₃ ⁻ . The polycarbonate thus produced has a relative viscosity of 1.293; saponifiable chlorine: <2 ppm;
Phenolic OH end groups: 140 ppm; sodium:
<0.5 ppm; yellowness index: 1.8.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jürgen Kaderka Germany 47829 Krefuert Karl-de Weisberg-Schutlerse 28 (72) Inventor Thomas Fitzcher Germany 47809 Krefert Emile-Fuinendengen-Schutrase 2

Claims (4)

[Claims] 1. Phosgene, diphenol, chain stopper,
And optionally from a branching agent, an aqueous solution of an alkali metal salt of the diphenol, a polycondensation catalyst is used in the presence of a solvent or solvent mixture that dissolves the aromatic oligocarbonate and polycarbonate and is itself immiscible with water. In a process for producing a thermoplastic aromatic polycarbonate by interfacial condensation by changing the phase ratio and performing phosgenation at a pH value of 8 to 14 in two or more process steps, reaction from a crude polycarbonate solution with an acid A process for producing a thermoplastic aromatic polycarbonate characterized in that the extracted catalyst is reused directly, that is, without being isolated or purified. 2. The manufacturing method according to claim 1, wherein washing is carried out countercurrently in order to reduce the amount of water. 3. The production method according to claim 1, wherein hydrochloric acid is used as an acid. 4. The production method according to claim 1, wherein a static mixer is used as a mixing device for reactively extracting the catalyst.