EP0000904B1 - Recovery of high value polycarbonate from polycarbonate wastes - Google Patents

Recovery of high value polycarbonate from polycarbonate wastes Download PDF

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Publication number
EP0000904B1
EP0000904B1 EP78100635A EP78100635A EP0000904B1 EP 0000904 B1 EP0000904 B1 EP 0000904B1 EP 78100635 A EP78100635 A EP 78100635A EP 78100635 A EP78100635 A EP 78100635A EP 0000904 B1 EP0000904 B1 EP 0000904B1
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Prior art keywords
polycarbonate
bis
hydroxyphenyl
saponification
solution
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German (de)
French (fr)
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EP0000904A1 (en
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Karsten Dr. Idel
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Bayer AG
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Bayer AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
    • C07C37/64—Preparation of O-metal compounds with O-metal group bound to a carbon atom belonging to a six-membered aromatic ring
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
    • C07C37/01—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by replacing functional groups bound to a six-membered aromatic ring by hydroxy groups, e.g. by hydrolysis
    • C07C37/055—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by replacing functional groups bound to a six-membered aromatic ring by hydroxy groups, e.g. by hydrolysis the substituted group being bound to oxygen, e.g. ether group
    • C07C37/0555—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by replacing functional groups bound to a six-membered aromatic ring by hydroxy groups, e.g. by hydrolysis the substituted group being bound to oxygen, e.g. ether group being esterified hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
    • C08G64/04—Aromatic polycarbonates
    • C08G64/06—Aromatic polycarbonates not containing aliphatic unsaturation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G64/00—Macromolecular compounds obtained by reactions forming a carbonic ester link in the main chain of the macromolecule
    • C08G64/40—Post-polymerisation treatment

Definitions

  • the present invention relates to a process for the recovery of aromatic, high molecular weight, thermoplastic polycarbonates from polycarbonate waste, the polycarbonate waste being present both purely as a transparent natural material and also together with organic and in particular inorganic dyes and / or other additives or as an alloy in combination with other thermoplastic materials can.
  • the 4,4'-dioxy-diarylalkanes are cleaved by means of alcohols, acid anhydrides or small amounts of basic catalysts according to some. receive complex cleaning procedures.
  • the cleavage is achieved by adding phenols or diaryl carbonates in the presence of metal oxide catalysts and temperatures above 180 ° C. At these temperatures, especially in the presence of metal oxide catalysts, there is a risk of side reactions, and extensive cleaning operations are necessary to obtain clean starting substances.
  • polycarbonates are saponified gently both in pure or colored form and as polymer alloys in a smooth one-pot reaction and, if appropriate after filtering off additives, dyes, etc. or alloy constituents, immediately afterwards in a smooth one-pot reaction in the same reaction media to high-molecular, thermoplastic and can dissolve soluble polycarbonates.
  • later disruptive catalysts and under gentle thermal conditions polycarbonates were thus cleaved and the reaction mixture remaining after the cleavage was directly converted back to polycarbonate synthesis using the phase interface process without any intermediate purification.
  • a water-immiscible solvent commonly used in the phase interface condensation of polycarbonates, e.g.
  • Methylene chloride or chlorobenzene can be condensed directly by introducing phosgene without any intermediate cleaning.
  • the pH of the alkaline phase should be kept between 9 and 14 depending on the type of diphenol.
  • tertiary amines such as e.g. Triethylamine, tributylamine, N-alkylpiperidine or ammonium, sulfonium, phosphonium or arsonium compounds or nitrogen hetaryls such as pyridine are used.
  • the monohydric phenols present at the chain end in polycarbonates are found as cleavage products after the saponification step in the alkaline reaction medium and, during or after the phosgenation, are fully incorporated again as chain limiters, so that the resynthesized polycarbonates achieve the same solution viscosity as the polycarbonate wastes converted as starting material. If other solution viscosities are to be set, an additional amount of free bisphenol can be added for a desired higher solution viscosity and an additional amount of monohydric phenol can be added for a lower solution viscosity.
  • condensed compounds with more than two condensable functional groups such as e.g. Tris or tetraphenols, which are incorporated as branching agents in polycarbonates, are fully incorporated again in the resynthesis of the polycarbonates.
  • a change in the branching concentration in the recovered polycarbonate is again possible by adding an additional amount of branching agent or free bisphenol to the reaction medium before the phosgenation.
  • the present invention thus relates to a process for the recovery of aromatic, high molecular weight, thermoplastic polycarbonates from polycarbonate waste by degradation and repolycondensation, which is characterized in that the polycarbonate waste in bulk or in solution at temperatures between 25 ° C and 220 ° C, if necessary, under Saponified under pressure, separated from unsaponifiable constituents and then the saponification mixture is phosgenized and polycondensed without further purification and workup steps using the methods of two-phase interfacial polycondensation.
  • Polycarbonate waste is understood to mean all polycarbonate plastic articles that are no longer usable, but also the residues, waste products, waste, etc. that are produced during the manufacture and deformation of the polycarbonate plastic.
  • aromatic polycarbonates which can be worked up as polycarbonate wastes can also be incorporated by incorporating small amounts, preferably amounts between 0.05 and 2.0 mol% (based on diphenols used), of three- or more than three-functional compounds, in particular those with three or more than three phenolic hydroxyl groups, for example by the incorporation of phloroglucin, 1,3,5-tri- (4-hydroxyphenyl) benzene, 1,1,1-tri- (4-hydroxyphenyl) -ethane or 1,4-bis (4,4'-dihydroxytriphenylmethyl) benzene.
  • the aromatic polycarbonates which can be worked up as polycarbonate wastes generally have average weight-average molecular weights Mw of 10,000 to more than 200,000, preferably 20,000 to 80,000, determined by measuring the rel. Viscosity in CH Z CI Z at 25 ° C and a concentration of 0.5% by weight.
  • the molecular weights of the polycarbonates can be regulated in a conventional manner, for example by incorporating phenol, tribromophenol or p-tert-butylphenol.
  • polycarbonates that can be processed as polycarbonate waste can also be present as mixtures of different polycarbonates, for example mixed with fractions of low molecular weight polycarbonates, or also as polymer alloys, for example with polymers or copolymers based on styrene, styrene-acrylonitrile, acrylonitrile-butadiene-styrene or butadiene rubber.
  • the polycarbonate waste is saponified in bulk or in solution, the solvents used being the customary solvents, such as methylene chloride or chlorobenzene, which are suitable for polycarbonate production by the two-phase interface process.
  • the solvents used being the customary solvents, such as methylene chloride or chlorobenzene, which are suitable for polycarbonate production by the two-phase interface process.
  • the saponification takes place in an alkaline aqueous reaction medium, the saponification in substance being heterogeneous and the saponification in solution taking place at the interface of the two-phase system, the latter proceeding more cheaply and more rapidly.
  • aqueous reaction medium preferably between 25 and 100 moles of water per mole of polycarbonate structural unit to be saponified are used.
  • AI bass saponification agents serve e.g. Sodium hydroxide, potassium hydroxide, calcium oxide, preferably sodium hydroxide.
  • the saponification takes place at temperatures between 25 ° and 220 ° C and, if appropriate, using excess pressure up to preferably 100 atmospheres.
  • the amount of basic saponification agents is between 0.01 and 15 times the molar amount, based on the moles of aromatic dihydroxy compound formed; the pH of the saponification medium is between 9 and 14; the duration of saponification, depending on the steric shielding of the carbonate structure, between 0.5 and rnax. 20 hours.
  • Phosphites or phosphines can also be added as catalysts.
  • the polycarbonate wastes contain unsaponifiable components such as lubricants, stabilizers, pigments, dyes, fillers such as glass powder, quartz products, graphite, molybdenum sulfide, metal powder, powder of high-melting plastics such as polytetraethylene powder, natural fibers such as asbestos, and also glass fibers of various types, metal threads etc. after filtration, these are separated in a known manner, for example by filtration.
  • unsaponifiable components such as lubricants, stabilizers, pigments, dyes, fillers such as glass powder, quartz products, graphite, molybdenum sulfide, metal powder, powder of high-melting plastics such as polytetraethylene powder, natural fibers such as asbestos, and also glass fibers of various types, metal threads etc. after filtration, these are separated in a known manner, for example by filtration.
  • the one- or two-phase solutions resulting from the saponification of the polycarbonate wastes can be used directly for the polycarbonate production according to the interfacial process, optionally adding the customary polycarbonate solvents such as methylene chloride or chlorobenzene and the pH of the aqueous solution between 9 and 14 is set.
  • the customary polycarbonate solvents such as methylene chloride or chlorobenzene
  • the subsequent phosgenation is usually carried out at room temperature, a phosgene amount of 1 to 3 moles, based on 1 mole of diphenol, preferably being used.
  • the duration of phosgenation is a maximum of 1 hour.
  • Tertiary amines or other polycondensation catalysts are used in amounts between 0.01 and 10 mol%, based on the moles of diphenols, before or in particular after Phosgenation added.
  • the polycondensation then takes place in the usual manner at temperatures between 20 ° and 40 ° C and, depending on the diphenol used, is complete after a period of 1-5 hours.
  • the duration of saponification and the amount of base used are directly related. As the table below shows, the amount of caustic soda used can be reduced at the cost of extended saponification times.
  • the saponification was carried out in the interface: 25.4 g of polycarbonate from Example 1 were dissolved in 300 ml of chlorobenzene and mixed with 15 N sodium hydroxide solution. The time until the polycarbonate was completely hydrolyzed was measured:
  • the saponification can also be carried out under pressure. 101.6 g of polycarbonate from Example 1, 400 ml of dist. Water and 2.26 g of 45% sodium hydroxide solution are heated in an autoclave to 210 ° C. at 50 bar pressure in 1 hour and held there for 2 hours. 840 g of 6.2% sodium hydroxide solution and 1500 ml of methylene chloride are added to the resulting mixture. While maintaining a pH of 13-14, 60 g of phosgene are introduced in 1 h and then condensed for 1 h after the addition of 6 ml of 4% aqueous triethylamine. The reaction mixture is worked up according to Example 1.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
  • Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Description

Die vorliegende Erfindung betrifft ein Verfahren zur Rückgewinnung von aromatischen, hochmolekularen, thermoplastischen Polycarbonaten aus Polycarbonatabfällen, wobei die Polycarbonatabfälle sowohl rein als transparentes Naturmaterial als auch zusammen mit organischen und insbesondere anorganischen Farbstoffen und/oder anderen Additiven oder als Legierung im Verbund mit anderen thermoplastischen Materialien vorliegen können.The present invention relates to a process for the recovery of aromatic, high molecular weight, thermoplastic polycarbonates from polycarbonate waste, the polycarbonate waste being present both purely as a transparent natural material and also together with organic and in particular inorganic dyes and / or other additives or as an alloy in combination with other thermoplastic materials can.

Aufgrund der fortschreitenden Verknappung von Rohstoffresourcen und den daraus resultierenden Rhostoffpreiserhöhungen werden Verfahren zur Aufarbeitung von nicht mehr verwendungsfähigen Kunststoffgebrauchsartikeln im Sinne einer Rückgewinnung entweder von Ausgangssubstanzen oder direkt des ursprünglichen Kunststoffes immer wichtiger.Due to the progressive shortage of raw material resources and the resulting increases in raw material prices, processes for processing plastic consumables that are no longer usable are becoming increasingly important in terms of recovering either starting materials or directly the original plastic.

So beschreibt E. Bullack in den Patentschriften DDR 45575, 46282, 45599, 45600 und 46353 Verfahren der Aufarbeitung von Polycarbonaten insbesondere im Hinblick auf die Gewinnung von 4,4'-Dioxy-diaryl-alkanen als Ausgangssubstanzen für die Polycarbonatsynthese.E. Bullack, for example, in the German patent documents GDR 45575, 46282, 45599, 45600 and 46353 describes processes for working up polycarbonates, in particular with a view to obtaining 4,4'-dioxy-diarylalkanes as starting substances for polycarbonate synthesis.

Gemäß den Patentschriften DDR 45575, 46282 und 45599 werden die 4,4'-Dioxy-diarylalkane über Spaltung mittels Alkoholen, Säureanhydriden oder geringen Mengen basischer Katalysatoren nach z.T. aufwendigen Reinigungsverfahren erhalten. Gemäß den Patentschriften 45600 und 46353 wird die Spaltung durch Zugabe von Phenolen oder Diarylcarbonaten bei Anwesenheit von Metalloxid-Katalysatoren und Temperaturen über 180°C erreicht. Bei diesen Temperaturen besteht insbesondere bei Anwesenheit von Metalloxid-Katalysatoren die Gefahr von Nebenreaktionen, und umfangreiche Reinigungsoperationen sind zur Gewinnung sauberer Ausgangssubstanzen nötig.According to the patents GDR 45575, 46282 and 45599, the 4,4'-dioxy-diarylalkanes are cleaved by means of alcohols, acid anhydrides or small amounts of basic catalysts according to some. receive complex cleaning procedures. According to the patents 45600 and 46353, the cleavage is achieved by adding phenols or diaryl carbonates in the presence of metal oxide catalysts and temperatures above 180 ° C. At these temperatures, especially in the presence of metal oxide catalysts, there is a risk of side reactions, and extensive cleaning operations are necessary to obtain clean starting substances.

Überraschenderweise wurde gefunden, daß man Polycarbonate sowohl in reiner oder eingefärbter Form als auch als Polymerlegeirungen in einer glatt verlaufenden Eintopfreaktion schonend verseifen und gegebenenfalls nach Abfiltrieren von Additiven, Farbstoffen usw. oder Legierungsbestandteilen direkt anschließend in einer glatten Eintopfreaktion in gleichen Reaktionsmedien wieder zu hochmolekularen, thermoplastischen und löslichen Polycarbonaten aufphosgenieren kann. Ohne Zusatz später störender Katalysatoren und unter schonenden thermischen Bedingungen wurden somit Polycarbonate gespalten und das nach der Spaltung verbleibende Reaktionsgemisch ohne jede Zwischenreinigung direkt wieder zur Polycarbonatsynthese nach dem Phasengrenzflächenverfahren umgesetzt. Nach Zugabe eines nicht mit Wasser mischbaren, in der Phasengrenzflächenkondensation von Polycarbonaten gebräuchlichen Lösungsmittels wie z.B. Methylenechloride oder Chlorbenzol kann ohne jede Zwischenreinigung durch Einleiten von Phosgen direkt aufkondensiert werden. Der pH-Wert der alkalischen Phase sollte dabei je nach Art des Diphenols zwischen 9 und 14 gehalten werden. Üblicherweise werden vor und insbesondere nach der Phosgenierung tertiäre Amine wie z.B. Triäthylamin, Tributylamin, N-Alkylpiperidin oder Ammonium-, Sulfonium-, Phosphonium- oder Arsoniumverbindungen oder auch Stickstoffhetaryle wie beispielsweise Pyridin eingesetzt.Surprisingly, it has been found that polycarbonates are saponified gently both in pure or colored form and as polymer alloys in a smooth one-pot reaction and, if appropriate after filtering off additives, dyes, etc. or alloy constituents, immediately afterwards in a smooth one-pot reaction in the same reaction media to high-molecular, thermoplastic and can dissolve soluble polycarbonates. Without the addition of later disruptive catalysts and under gentle thermal conditions, polycarbonates were thus cleaved and the reaction mixture remaining after the cleavage was directly converted back to polycarbonate synthesis using the phase interface process without any intermediate purification. After adding a water-immiscible solvent, commonly used in the phase interface condensation of polycarbonates, e.g. Methylene chloride or chlorobenzene can be condensed directly by introducing phosgene without any intermediate cleaning. The pH of the alkaline phase should be kept between 9 and 14 depending on the type of diphenol. Usually, before and especially after phosgenation, tertiary amines such as e.g. Triethylamine, tributylamine, N-alkylpiperidine or ammonium, sulfonium, phosphonium or arsonium compounds or nitrogen hetaryls such as pyridine are used.

Die bei Polycarbonaten am Kettenende vorliegenden einwertigen Phenole befinden sich als Spaltprodukte nach dem Verseifungsschritt im alkalischen Reaktionsmedium und bauen während oder nach der Phosgenierung wieder vollständig als Kettenbegrenzer ein, so daß die resynthetisierten Polycarbonate die gleiche Lösungsviskosität wie die als Ausgangsmaterial umgesetzten Polycarbonatabfälle erreichen. Sollen andere Lösungsviskositäten eingestellt werden, so kann für eine gewünschte höhere Lösungsviskosität eine zusätzliche Menge an freiem Bisphenol und für eine niedrigere Lösungsviskosität eine zusätzliche Menge an einwertigem Phenol zudosiert werden.The monohydric phenols present at the chain end in polycarbonates are found as cleavage products after the saponification step in the alkaline reaction medium and, during or after the phosgenation, are fully incorporated again as chain limiters, so that the resynthesized polycarbonates achieve the same solution viscosity as the polycarbonate wastes converted as starting material. If other solution viscosities are to be set, an additional amount of free bisphenol can be added for a desired higher solution viscosity and an additional amount of monohydric phenol can be added for a lower solution viscosity.

Ebenso werden einkondensierte Verbindungen mit mehr als zwei kondensationsfähigen funktionellen Gruppen wie z.B. Trisoder Tetraphenole, die als Verzweiger in Polycarbonate eingebaut sind, bei der Resynthese der Polycarbonate wieder vollständig eingebaut. Eine Änderung der Verzweigerkonzentration im rückgewonnenen Polycarbonat bietet sich wieder durch Zugabe einer zusätzlichen Menge an Verzweiger oder an freiem Bisphenol zu dem Reaktionsmedium vor der Phosgenierung an.Also condensed compounds with more than two condensable functional groups such as e.g. Tris or tetraphenols, which are incorporated as branching agents in polycarbonates, are fully incorporated again in the resynthesis of the polycarbonates. A change in the branching concentration in the recovered polycarbonate is again possible by adding an additional amount of branching agent or free bisphenol to the reaction medium before the phosgenation.

Gegenstand der vorliegenden Erfindung ist somit ein Verfahren zur Rückgewinnung von aromatischen, hochmolekularen, thermoplastischen Polycarbonaten aus Polycarbonatabfällen durch Abbau und Repolykondensation, das dadurch gekennzeichnet ist, daß man die Polycarbonatabfälle in Substanz oder in Lösung bei Temperaturen zwischen 25°C und 220°C gegebenenfalls unter Druck verseift, von unverseifbaren Bestandteilen abtrennt und anschließend das Verseifungsgemisch ohne weitere Reinigungs- und Aufarbeitungsschritte nach den Methoden der Zweiphasengrenzflächenpolykondensation phosgeniert und polykondensiert.The present invention thus relates to a process for the recovery of aromatic, high molecular weight, thermoplastic polycarbonates from polycarbonate waste by degradation and repolycondensation, which is characterized in that the polycarbonate waste in bulk or in solution at temperatures between 25 ° C and 220 ° C, if necessary, under Saponified under pressure, separated from unsaponifiable constituents and then the saponification mixture is phosgenized and polycondensed without further purification and workup steps using the methods of two-phase interfacial polycondensation.

Als Polycarbonatabfälle sind alle nicht mehr verwendbaren Polycarbonatkunststoffartikel, aber auch die bei der Herstellung und Verformung des Polycarbonatkunststoff anfallenden Rückstände, Abfallprodukte, Verschnitt etc. zu verstehen.Polycarbonate waste is understood to mean all polycarbonate plastic articles that are no longer usable, but also the residues, waste products, waste, etc. that are produced during the manufacture and deformation of the polycarbonate plastic.

Die für die Aufarbeitung geeigneten Polycarbonatabfälle resultieren aus aromatischen Homopolycarbonaten und Copolycarbonaten, denen z.B. ein oder mehrere der folgenden Diphenole zugrunde liegen:

  • Hydrochinon
  • Resorcin
  • Dihydroxydiphenyle
  • Bis-(hydroxyphenyl)-alkane
  • Bis-(hydroxyphenyl)-cycloalkane
  • Bis-(hydroxyphenyl)-sulfide
  • Bis-(hydroxyphenyl)-äther
  • Bis-(hydroxyphenyi)-ketone
  • Bis-(hydroxyphenyl)-sulfoxide
  • Bis-(hydroxyphenyl)-sulfone
  • (x,a' - Bis - (hydroxyphenyl) - diisopropylbenzole

sowie beispielsweise deren kernhalogenierte Verbindungen. Diese und weitere geeignete Diphenole sind z.B. in der US-Patentschrift 3 028 365, und in der Monographie "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York, 1964" beschrieben.The poly suitable for processing Carbonate waste results from aromatic homopolycarbonates and copolycarbonates, which are based, for example, on one or more of the following diphenols:
  • Hydroquinone
  • Resorcinol
  • Dihydroxydiphenyls
  • Bis (hydroxyphenyl) alkanes
  • Bis (hydroxyphenyl) cycloalkanes
  • Bis (hydroxyphenyl) sulfides
  • Bis (hydroxyphenyl) ether
  • Bis (hydroxyphenyi) ketones
  • Bis (hydroxyphenyl) sulfoxides
  • Bis (hydroxyphenyl) sulfones
  • (x, a '- bis - (hydroxyphenyl) diisopropylbenzenes

as well as, for example, their nuclear halogenated compounds. These and other suitable diphenols are described, for example, in US Pat. No. 3,028,365 and in the monograph "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York, 1964".

Bevorzugte Diphenole sind z.B.:

  • 4,4'-Dihydroxydiphenyl
  • 2,2 - Bis - (4 - hydroxyphenyl) - propan (Bisphenol - A)
  • 2,4-Bis-(4-hydroxyphenyi)-2-methytbutan
  • 1,1-Bis-(4-hydroxyphenyl)-cyclohexan
  • α,α'-Bis-(4-hydroxyphenyl)-p-düsopropylbenzol
  • 2,2-Bis-(3-chlor-4-hydroxyphenyl)-propan
  • 2,2-Bis-(3,5-dichlor-4-hydroxyphenyl)-prcpan
  • 2,2-Bis-(3,5-dibrom-4-hydroxyphenyl)-propan.
Preferred diphenols are, for example:
  • 4,4'-dihydroxydiphenyl
  • 2,2 - bis - (4-hydroxyphenyl) propane (bisphenol - A)
  • 2,4-bis (4-hydroxyphenyi) -2-methytbutane
  • 1,1-bis (4-hydroxyphenyl) cyclohexane
  • α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene
  • 2,2-bis (3-chloro-4-hydroxyphenyl) propane
  • 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane
  • 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane.

Die als Polycarbonatabfälle aufarbeitbaren aromatischen Polycarbonate können auch durch den Einbau geringer Mengen, vorzugsweise von Mengen zwischen 0,05 und 2,0 Mol-% (bezogen auf eingesetzte Diphenole), an drei- oder mehr als drei-funktionellen Verbindungen, insbesondere solchen mit drei oder mehr als drei phenolischen Hydroxygruppen verzweigt sein, beispielsweise durch den Einbau von Phloroglucin, 1,3,5-Tri-(4-hydroxy-phenyl)-benzol, 1,1,1-Tri-(4-hydroxyphenyl)-äthan oder 1,4-Bis-(4,4'-dihydroxytriphenyl-methyl)-benzol.The aromatic polycarbonates which can be worked up as polycarbonate wastes can also be incorporated by incorporating small amounts, preferably amounts between 0.05 and 2.0 mol% (based on diphenols used), of three- or more than three-functional compounds, in particular those with three or more than three phenolic hydroxyl groups, for example by the incorporation of phloroglucin, 1,3,5-tri- (4-hydroxyphenyl) benzene, 1,1,1-tri- (4-hydroxyphenyl) -ethane or 1,4-bis (4,4'-dihydroxytriphenylmethyl) benzene.

Die als Polycarbonatabfälle aufarbeitbaren aromatischen Polycarbonate haben in der Regel mittlere Gewichtsmittelmolekulargewichte Mw von 10 000 bis über 200 000, vorzugsweise von 20 000 bis 80 000, ermittelt durch Messungen der rel. Viskosität in CHZCIZ bei 25°C und einer Konzentration von 0,5 Gew.-%.The aromatic polycarbonates which can be worked up as polycarbonate wastes generally have average weight-average molecular weights Mw of 10,000 to more than 200,000, preferably 20,000 to 80,000, determined by measuring the rel. Viscosity in CH Z CI Z at 25 ° C and a concentration of 0.5% by weight.

Die Molekulargewichte der Polycarbonate können in üblicher Weise geregelt sein, beispielsweise durch den Einbau von Phenol, Tribromphenol oder p-tert.-Butylphenol.The molecular weights of the polycarbonates can be regulated in a conventional manner, for example by incorporating phenol, tribromophenol or p-tert-butylphenol.

Die als Polycarbonatabfälle aufarbeitbaren Polycarbonate können auch als Gemische von verschiedenen Polycarbonaten, beispielsweise mit Anteilen niedermolekularer Polycarbonate vermischt, vorliegen, oder auch als Polymerlegierungen beispielsweise mit Polymerisaten oder Copolymerisaten auf Basis Styrol, Styrol-Acrylnitril, Acrylnitril-Butadien-Styrol oder Butadien-Kautschuk vorliegen.The polycarbonates that can be processed as polycarbonate waste can also be present as mixtures of different polycarbonates, for example mixed with fractions of low molecular weight polycarbonates, or also as polymer alloys, for example with polymers or copolymers based on styrene, styrene-acrylonitrile, acrylonitrile-butadiene-styrene or butadiene rubber.

Die Verseifung der Polycarbonatabfälle erfolgt in Substanz oder in Lösung, wobei als Lösungsmittel die üblichen, für die Polycarbonatherstellung nach dem Zweiphasengrenzflächenverfahren geeigneten Lösungsmittel wie Methylenchlorid oder Chlorbenzol verwendet werden.The polycarbonate waste is saponified in bulk or in solution, the solvents used being the customary solvents, such as methylene chloride or chlorobenzene, which are suitable for polycarbonate production by the two-phase interface process.

Die Verseifung erfolgt in alkalischem wäßrigem Reaktionsmedium, wobei die Verseifung in Substanz heterogen und die Verseifung in Lösung an der Grenzfläche des Zweiphasensystems erfolgt, wobei letztere günstiger und rascher verläuft. Bezüglich des wäßrigen Reaktionsmediums werden vorzugsweise zwischen 25 und 100 Mol Wasser pro Mol zu verseifender Polycarbonat-Struktureinheit eingesetzt.The saponification takes place in an alkaline aqueous reaction medium, the saponification in substance being heterogeneous and the saponification in solution taking place at the interface of the two-phase system, the latter proceeding more cheaply and more rapidly. With regard to the aqueous reaction medium, preferably between 25 and 100 moles of water per mole of polycarbonate structural unit to be saponified are used.

AI bassiche Verseifungsagenzien dienen z.B. Natriumhydroxid, Kaliumhydroxid, Calciumoxid, vorzugsweise Natriumhydroxid.AI bass saponification agents serve e.g. Sodium hydroxide, potassium hydroxide, calcium oxide, preferably sodium hydroxide.

Die Verseifung erfolgt bei Temperaturen zwischen 25° und 220°C und gegebenenfalls unter Verwendung von Überdruck bis vorzugsweise 100 Atmosphären.The saponification takes place at temperatures between 25 ° and 220 ° C and, if appropriate, using excess pressure up to preferably 100 atmospheres.

Die Menge an basischen Verseifungsagenzien liegt zwischen der 0,01 und 15- fachen Molmenge, bezogen auf die Mole entstehender aromatischer Dihydroxyverbindung; der pH-Wert des Verseifungsmediums liegt zwischen 9 und 14; die Dauer der Verseifung je nach sterischer Abschirmung der Carbonatstruktur zwischen 0,5 und rnax. 20 Stunden.The amount of basic saponification agents is between 0.01 and 15 times the molar amount, based on the moles of aromatic dihydroxy compound formed; the pH of the saponification medium is between 9 and 14; the duration of saponification, depending on the steric shielding of the carbonate structure, between 0.5 and rnax. 20 hours.

Es können als Katalysatoren zusätzlich Phosphite oder Phosphine zugesetz werden.Phosphites or phosphines can also be added as catalysts.

Enthalten die Polycarbonatabfälle unverseifbare Bestandteile wie Gleitmittel, Stabilisatoren, Pigmente, Farbstoffe, Füllstoffe wie Glaspulver, Quarzerzeugnisse, Graphit, Molybdänsulfid, Metallpulver, Pulver höherschmelzender Kunststoffe wie Polytetra- äthylenpulver, natürliche Fasern wie Asbest, ferner Glasfasern der verschiedensten Art, Metallfäden etc., so werden diese nach erfolgter Filtration auf bekannte Weise, beispielsweise durch Filtration abgetrennt.Do the polycarbonate wastes contain unsaponifiable components such as lubricants, stabilizers, pigments, dyes, fillers such as glass powder, quartz products, graphite, molybdenum sulfide, metal powder, powder of high-melting plastics such as polytetraethylene powder, natural fibers such as asbestos, and also glass fibers of various types, metal threads etc. after filtration, these are separated in a known manner, for example by filtration.

Die nach der Verseifung der Polycarbonatabfälle resultierenden ein- oder zweiphasigen Lösungen können direkt für die Polycarbonatherstellung nach dem Phasengrenzflächenverfahren eingesetzt werden, wobei gegebenenfalls die gebräuchlichen Polycarbonat-Lösungsmittel wie Methylenchlorid oder Chlorbenzol zugesetzt werden und der pH-Wert der wäßrigen Lösung je nach Anforderung zwischen 9 und 14 eingestellt wird.The one- or two-phase solutions resulting from the saponification of the polycarbonate wastes can be used directly for the polycarbonate production according to the interfacial process, optionally adding the customary polycarbonate solvents such as methylene chloride or chlorobenzene and the pH of the aqueous solution between 9 and 14 is set.

Die nachfolgende Phosgenierung erfolgt gewöhnlich bei Raumtemperatur, wobei vorzugsweise eine Phosgennlenge von 1 bis 3 Mol, bezogen auf 1 Mol Diphenol, eingesetzt wird.The subsequent phosgenation is usually carried out at room temperature, a phosgene amount of 1 to 3 moles, based on 1 mole of diphenol, preferably being used.

Die Dauer der Phosgenierung beträgt max.1 Stunde.The duration of phosgenation is a maximum of 1 hour.

Tertiäre Amine oder andere Polykondensationskatalysatoren werden in Mengen zwischen 0,01 und 10 Mol-%, bezogen auf die Mole Diphenole, vor oder insbesondere nach der Phosgenierung zugesetzt.Tertiary amines or other polycondensation catalysts are used in amounts between 0.01 and 10 mol%, based on the moles of diphenols, before or in particular after Phosgenation added.

Die Polykondensation erfolgt anschließend in der üblichen Weise bei Temperaturen zwischen 20° und 40°C und ist je nach eingesetztem Diphenol nach einem Zeitraum von 1-5 Std. beendet.The polycondensation then takes place in the usual manner at temperatures between 20 ° and 40 ° C and, depending on the diphenol used, is complete after a period of 1-5 hours.

Die erhaltenen Polycarbonatlösungen werden wie üblich aufgearbeitet und das Polycar- bonat in der üblichen Weise isoliert.The polycarbonate solutions obtained are worked up as usual and the Polycar - carbonate in the usual way isolated.

BEISPIEL 1EXAMPLE 1

25,4 g Polycarbonat aus 2,2-Bis-(4-hydroxyphenyl)-propan mit einer Lösungsviskosität von ηrel = 1,288 (gemessen an Lösungen von 0,5 g Polycarbonat in 100 ml Methylenchlorid) werden in Granulatform in 80 ml 15 n Natronlauge gegeben. Das Reaktionsgemisch wird 4 Std. auf 100°C erhitzt. In dieser Zeit wird eine vollständige Spaltung des Polycarbonats bis zum Monomerbaustein Bisphenol A erreicht. Gibt man 500 ml dest. Wasser zu der resultierenden Suspension, so erhält man eine klare alkalische Lösung des Bisphenol A, die nach Zugabe von 500 ml Methylenchlorid nach den üblichen Methoden der Phasengrenzflächenkondensation phosgeniert werden kann.25.4 g of polycarbonate from 2,2-bis (4-hydroxyphenyl) propane with a solution viscosity of η rel = 1.288 (measured on solutions of 0.5 g of polycarbonate in 100 ml of methylene chloride) are granulated in 80 ml of 15 ml Given sodium hydroxide solution. The reaction mixture is heated to 100 ° C. for 4 hours. During this time, the polycarbonate is completely cleaved down to the bisphenol A monomer unit. If 500 ml of dist. Water to the resulting suspension, so you get a clear alkaline solution of bisphenol A, which can be phosgenated after the addition of 500 ml of methylene chloride by the usual methods of phase interface condensation.

Hierzu werden in 1 Stunde bei 25°C 15 g Phosgen unter Einstellung eines pH-Wertes von 13-14 eingeleitet und anschließend wird nach Zugabe von 1,5 ml einer 4 96igen wäßrigen Triäthylaminlösung noch 1 h aufkondensiert. Die organische Phase wird abgetrennt, zweimal mit 2 96iger Phosphorsäure und dann mit dest. Wasser elektrolytfrei gewaschen. Nach dem Abdampfen des Lösungsmittels erhält man 24 g Polycarbonat mit einer ηrel = 1,295. Das recyclisierte Polycarbonat zeigt die gleichen guten mechan. und rheologischen Eigenschaften wie das Ausgangsmaterial.For this purpose, 15 g of phosgene are introduced in 1 hour at 25 ° C., with a pH of 13-14, and then, after addition of 1.5 ml of a 4,96 aqueous triethylamine solution, condensation is continued for 1 hour. The organic phase is separated, twice with 2 96% phosphoric acid and then with dist. Washed water free of electrolyte. After evaporation of the solvent, 24 g of polycarbonate with an η rel = 1.295 are obtained. The recycled polycarbonate shows the same good mechan. and rheological properties like the starting material.

BEISPIEL 2EXAMPLE 2

25,4 g Polycarbonat aus 2,2-Bis-(4-hydroxyphenyl)-propan des Beispiels 1 werden in Granulatform in 30 ml 15 n Natronlauge gegeben. Zusätzlich werden noch 2,5 g (10 Gew.- %) Triphenylphosphit zugesetzt und dann gemäß Beispiel 1 bei 100°C verseift. Durch Zusatz des Phosphits verkürzt sich die Zeit bis zur vollständigen Verseifung auf 2 Std. 45 min. Danach wird analog Beispiel 1 in der Phasengrenzfläche aufphosgeniert. Das zurückgewonnene Polycarbonat besitzt eine Lösungsviskosität von ηrel = 1,297 und zeigt nach Ausfällen aus der Methylenchloridlösung mittels Methanol in den mechanischen und reheologischen Eigenschaften keinen Unterschied zum Ausgangsmaterial.25.4 g of polycarbonate from 2,2-bis (4-hydroxyphenyl) propane from Example 1 are added in granular form in 30 ml of 15N sodium hydroxide solution. In addition, 2.5 g (10% by weight) of triphenyl phosphite are added and then saponified according to Example 1 at 100 ° C. By adding the phosphite, the time to complete saponification is reduced to 2 hours 45 minutes. Thereafter, analogous to Example 1, is phosgenated in the phase interface. The recovered polycarbonate has a solution viscosity of η rel = 1.297 and shows no difference in mechanical and rheological properties from the starting material after precipitation from the methylene chloride solution using methanol.

BEISPIEL 3EXAMPLE 3

25,4 g Polycarbonat aus 2,2-Bis-(4-hydroxyphenyl)-propan gemäß Beispiel 1 werden in 300 ml Chlorbenzol gelöst und 80 ml 15 n Natronlauge als alkalische Phase hinzugegeben. Das Gemisch wurde auf 100°C gebracht und die organische Phase in kurzen Abständen auf den Gehalt an noch unverseiftem Polycarbonat geprüft. Bereits nach 60 Min. war die Spaltung vollständig abgeschlossen und das Phasengrenzflächengemisch konnte direkt nach Zugabe von 350 ml Wasser analog Beispiel 1 phosgeniert und aufgearbeit werden. Man erhält 23,5 g eines Polycarbonats mit einer ηrel bon 1,315 und ähnlichem Eigenschaftsbild wie das Ausgansmaterial.25.4 g of polycarbonate from 2,2-bis (4-hydroxyphenyl) propane according to Example 1 are dissolved in 300 ml of chlorobenzene and 80 ml of 15N sodium hydroxide solution are added as an alkaline phase. The mixture was brought to 100 ° C. and the organic phase was checked at short intervals for the content of unsaponified polycarbonate. The cleavage was complete after only 60 minutes and the phase boundary mixture could be phosgenated and worked up analogously to Example 1 directly after adding 350 ml of water. 23.5 g of a polycarbonate having an η rel bon 1.315 and a property profile similar to that of the starting material are obtained.

Durch Zugabe von 450 mg p-tert.-Butylphenol als zusätzlichen Kettenabbrecher zum Verseifungsgemisch kann nach Phosgenierung und Aufkondensation die Lösungsviskosität von ηrel = 1,282 eingestellt werden.By adding 450 mg of p-tert-butylphenol as an additional chain terminator to the saponification mixture, the solution viscosity of η rel = 1.282 can be adjusted after phosgenation and condensation.

BEISPIEL 4EXAMPLE 4

Verseifungsdauer und Menge der eingesetzten Base stehen in einem direkten Vorhältnis. Wie die untenstehende Tabelle zeigt, kann die eingesetzte Menge Natronlauge auf Kosten verlängerter Verseifungszeiten reduziert werden. Die Verseifung wurde in der Grenzfläche durchgeführt: 25,4 g Polycarbonat des Beispiels 1 wurden in 300 ml Chlorbenzol gelöst und mit wechselnden Mengen 15 n Natronlauge versetzt. Es wurde jeweils die Zeit bis zur vollständigen Verseifung des Polycarbonats gemessen:

Figure imgb0001
The duration of saponification and the amount of base used are directly related. As the table below shows, the amount of caustic soda used can be reduced at the cost of extended saponification times. The saponification was carried out in the interface: 25.4 g of polycarbonate from Example 1 were dissolved in 300 ml of chlorobenzene and mixed with 15 N sodium hydroxide solution. The time until the polycarbonate was completely hydrolyzed was measured:
Figure imgb0001

BEISPIEL 5EXAMPLE 5

Die Verseifung kann auch unter Druck durchgeführt werden. 101,6 g Polycarbonat des Beispiels 1, 400 ml dest. Wasser und 2,26 g 45 %ige Natronlauge werden in einem Autoklaven in 1 h auf 210°C bei 50 bar Druck erhitzt und 2 Std. dabei gehalten. Das erhaltene Gemisch wird mit 840 g 6,2 96iger Natronlauge und 1500 ml Methylenchlorid versetzt. Unter Einhaltung eines pH-Wertes von 13-14 werden 60 g Phosgen in 1 h eingeleitet und anschließend nach Zugabe von 6 ml 4 %igem wäßrigen Triäthylamin 1 h aufkondensiert. Das Reaktionsgemisch wird gemäß Beispiel 1 aufgearbeitet. Da bei der Druckverseifung vermutlich geringe Mengen monofunktioneller Monomerer abgespalten werden, beträgt die Lösungsviskosität des resultierenden Polycarbonats ηrel = 1,212. Durch zusätzliche Zugabe von 19 g. Bisphenol A zum Verseifungsgemisch und entsprechende Erhöhung der Anteile Phosgen und Triäthylamin kann ein Polycarbonat der gewünschten ηrel = 1,287 erhalten werden.The saponification can also be carried out under pressure. 101.6 g of polycarbonate from Example 1, 400 ml of dist. Water and 2.26 g of 45% sodium hydroxide solution are heated in an autoclave to 210 ° C. at 50 bar pressure in 1 hour and held there for 2 hours. 840 g of 6.2% sodium hydroxide solution and 1500 ml of methylene chloride are added to the resulting mixture. While maintaining a pH of 13-14, 60 g of phosgene are introduced in 1 h and then condensed for 1 h after the addition of 6 ml of 4% aqueous triethylamine. The reaction mixture is worked up according to Example 1. Since small amounts of monofunctional monomers are presumably split off during pressure saponification, the solution viscosity of the resulting polycar is bonats η rel = 1.212. By adding 19 g. Bisphenol A for the saponification mixture and a corresponding increase in the proportions of phosgene and triethylamine, a polycarbonate of the desired η rel = 1.287 can be obtained.

BEISPIEL 6EXAMPLE 6

27,9 g eines Polycarbonats auf Basis Bisphenol A (ηrel = 1,305) mit 10 Gew.-% Glasfaser wird mit 80 ml 15 n Natronlauge versetzt und das Gemisch auf 100°C erwärmt. Nach 3 h ist die Verseifung beendet. Man gibt 500 ml dest. H20 zu dem Verseifungsmisch und filtriert die verbleibende Glasfaser ab. Das Filtrat wird mit 500 ml Methylenchlorid versetzt und analog Beispiel 1 mit 15 g Phosgen versetzt und 1,5 ml einer 4 %igen wäßr. Triäthylaminlösung aufkondensiert. Nach der Aufarbeitung gemäß Beispiel 1 erhält man 10 g eines Glasfaserfreien Polycarbonats ηrel = 1,317. Das Polycarbonat zeigt das gleiche Eigenschaftsbild wie ein Polycarbonat entsprechender Kettenlänge, das durch übliche Kondensation von Bisphenol A und Phosgen nach dem Phasengrenzflächenverfahren gewonnen wurde.27.9 g of a polycarbonate based on bisphenol A (η rel = 1.305) with 10% by weight of glass fiber are mixed with 80 ml of 15N sodium hydroxide solution and the mixture is heated to 100.degree. The saponification is complete after 3 hours. 500 ml of dist. H 2 0 to the saponification mixture and the remaining glass fiber is filtered off. The filtrate is mixed with 500 ml of methylene chloride and treated analogously to Example 1 with 15 g of phosgene and 1.5 ml of a 4% aq. Triethylamine solution condensed. After working up according to Example 1, 10 g of a glass fiber-free polycarbonate η rel = 1.317 are obtained. The polycarbonate shows the same property profile as a polycarbonate of corresponding chain length, which was obtained by the usual condensation of bisphenol A and phosgene using the phase interface process.

BEISPIEL 7EXAMPLE 7

25,4 g eines Polycarbonats auf Basis Bisphenol A mit einer Lösungsviskosität von ηrel = 1,367, das 0,2 Mol-%, bezogen auf die Anteile Diphenole, des tetrafunktionellen Verzweigers 1,4-Bis-(4,4'-Dihydroxytriphenyi- methyl)-benzol eingebaut enthält, wird mit 80 ml 15 n Natronlauge versetzt und 3 Std. bei 100°C gehalten. Danach gibt man 500 ml dest. H20 bis zur klaren Lösung und anschließend 500 ml Methylenchlorid hinzu. Das Verseifungsgemisch wird analog Beispiel 1 mit 15 g Phosgen versetzt und mit 1,5 ml einter 4 %igen wäßrigen Triäthylaminlösung aufkondensiert. Nach den üblichen Aufarbeitungsmethoden erhält man ein Polycarbonat mit einer Lösungsviskosität von ηrel = 1,375, das nach Spaltung und chromatographischer Untersuchung der Monomerbestandteile 0,2 Mol-% eines tetrafunktionellen Verzweigers eingebaut enthält.25.4 g of a polycarbonate based on bisphenol A with a solution viscosity of rel . contains methyl) -benzene, is mixed with 80 ml of 15N sodium hydroxide solution and kept at 100 ° C for 3 hours. Then 500 ml of dist. Add H20 to a clear solution and then 500 ml of methylene chloride. 15 g of phosgene are added to the saponification mixture analogously to Example 1 and condensed with 1.5 ml of 4% strength aqueous triethylamine solution. According to the usual work-up methods, a polycarbonate with a solution viscosity of η rel = 1.375 is obtained which, after cleavage and chromatographic examination of the monomer components, contains 0.2 mol% of a tetrafunctional branching agent.

BEISPIEL 8EXAMPLE 8

36,3 g einer Polymerlegierung, die sich aus 30 Gew.-% eines ABS-Polymeren und 70% eines Polycarbonats auf Basis Bisphenol A (ηrel. 1.292) zusammensetzt, werden mit 120 ml 15 n Natronlauge 10 Std. bei 100°C behandelt. Danach füllt man mit 500 ml dest. H20 auf und filtriert das ungelöste ABS-Polymerisat ab. Anschließend gibt man noch 500 ml Methylenchlorid zu dem Filtrat und leitet in 1 h bei Raumtemperatur 11 g Phosgen ein und kondensiert nach Zugabe von 1,5 ml einer 4 %igen wäßrigen Triäthylaminlösung noch 1 h auf. Man erhält nach den üblichen Aufarbeitungsmethoden 17 g des hochmolekularen, thermoplastischen Polycarbonats mit einer Lösungsviskosität ηrel = 1,305.36.3 g of a polymer alloy, which is composed of 30% by weight of an ABS polymer and 70% of a polycarbonate based on bisphenol A (η rel . 1,292), are mixed with 120 ml of 15N sodium hydroxide solution at 100 ° C. for 10 hours treated. Then you fill with 500 ml of dist. H 2 0 and the undissolved ABS polymer is filtered off. Then 500 ml of methylene chloride are added to the filtrate, 11 g of phosgene are passed in at room temperature in 1 hour and, after addition of 1.5 ml of a 4% strength aqueous triethylamine solution, the mixture is condensed for a further 1 hour. 17 g of the high molecular weight, thermoplastic polycarbonate with a solution viscosity η rel = 1.305 are obtained by the customary workup methods.

BEISPIEL 9EXAMPLE 9

25,4 g eines mit 0,35 Gew.-% Cadmiumselenid rot eingefärbten Polycarbonats auf Basis Bisphenol A (ηrel % 1,285) wird mit 80 ml Natronlauge versetzt und 3 Std. auf 100°C erwärmt. Danach wird mit 500 ml dest. H20 aufgefüllt und das ungelöste Farbpigment abfiltriert. Zu dem klaren Filtrat werden 500 ml Methylenchlorid gegeben und das Phasengrenzflächengemisch wie in Beispiel 1 phosgeniert und aufgearbeitet. Es verbleiben 22 g eines ungefärbten, thermoplast. Polycarbonats mit einer Lösungsviskostät von ηrel = 1,297.25.4 g of a polycarbonate based on bisphenol A (η rel % 1.285) colored red with 0.35% by weight of cadmium selenide is mixed with 80 ml of sodium hydroxide solution and heated to 100 ° C. for 3 hours. Then it is distilled with 500 ml. H 2 0 filled up and the undissolved color pigment filtered off. 500 ml of methylene chloride are added to the clear filtrate and the phase interface mixture is phosgenated and worked up as in Example 1. There remain 22 g of an undyed, thermoplastic. Polycarbonate with a solution viscosity of η rel = 1.297.

BEISPIEL 10EXAMPLE 10

27 g eines Copolycarbonats auf Basis Bisphenol A und Tetrabrom-Bisphenol A (5,3 Gew.-% Brom) (ηrel = 1,297) werden in 150 ml Chlorbenzol gelöst und 80 ml 15 n Natronlauge zudosiert. Nach 4 Std. wird die Verseifung beendet und man erhält nach Zugabe von 350 ml Methylenchlorid und 400 ml Wasser ein klares Phasengemisch. Zur Rückgewinnung des Polycarbonats werden 15 g Phosgen in 1 h bei Raumtemperatur eingeleitet. Am Ende der Phosgenierung sollte die Lösung einen pH-Wert von ca. 11-12 haben. Nach Zugabe von 0,43 ml Triäthylamin kondensiert man noch 1 h auf und arbeitet gemäß Beispiel 1 auf. Es resultiert ein bromhaltiges Polycarbonat (5,4 % Brom) mit einer Lösungsviskosität von ηrel = 1,285 und ähnlichen Eigenschaften wie das Ausgangsmaterial.27 g of a copolycarbonate based on bisphenol A and tetrabromo-bisphenol A (5.3% by weight bromine) (η rel = 1.297) are dissolved in 150 ml of chlorobenzene and 80 ml of 15N sodium hydroxide solution are metered in. After 4 hours, the hydrolysis is ended and a clear phase mixture is obtained after adding 350 ml of methylene chloride and 400 ml of water. To recover the polycarbonate, 15 g of phosgene are introduced in 1 h at room temperature. At the end of phosgenation, the solution should have a pH of approx. 11-12. After adding 0.43 ml of triethylamine, the mixture is condensed for a further 1 h and worked up according to Example 1. The result is a bromine-containing polycarbonate (5.4% bromine) with a solution viscosity of η rel = 1.285 and properties similar to those of the starting material.

Claims (1)

  1. A process for the recovery of aromatic, high molecular weight, thermoplastic polycarbonates from polycarbonate scrap by means of decomposition and repolycondensation, characterised in that the polycarbonate scrap is saponified in bulk or in solution at temperatures between 25°C and 220°C, optionally under pressure, the non-saponified constituents are separated off and the saponification mixture is then phosgenated and subjected to polycondensation according to the methods of two phase boundary polycondensation without any further purification steps and treatment steps.
EP78100635A 1977-08-20 1978-08-09 Recovery of high value polycarbonate from polycarbonate wastes Expired EP0000904B1 (en)

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EP0000904A1 (en) 1979-03-07
IT7850772A0 (en) 1978-08-18
JPS6051499B2 (en) 1985-11-14
JPS5448869A (en) 1979-04-17
DE2737693A1 (en) 1979-02-22
DE2860074D1 (en) 1980-11-13
IT1106890B (en) 1985-11-18
US4212774A (en) 1980-07-15

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