DE3323940A1 - Process for the purification of polymers - Google Patents

Process for the purification of polymers

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Publication number
DE3323940A1
DE3323940A1 DE19833323940 DE3323940A DE3323940A1 DE 3323940 A1 DE3323940 A1 DE 3323940A1 DE 19833323940 DE19833323940 DE 19833323940 DE 3323940 A DE3323940 A DE 3323940A DE 3323940 A1 DE3323940 A1 DE 3323940A1
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Prior art keywords
polymers
bar
supercritical
temperature
extraction
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DE19833323940
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German (de)
Inventor
Gero Dr. 6100 Darmstadt Braun
Klaus Dr. 6233 Kelkheim Kühlein
Hermann Dr. 6000 Frankfurt Schmitz
Rudolf Prof. Dr. 6231 Sulzbach Steiner
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Hoechst AG
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Hoechst AG
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Priority to DE19833323940 priority Critical patent/DE3323940A1/en
Publication of DE3323940A1 publication Critical patent/DE3323940A1/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/22—After-treatment of expandable particles; Forming foamed products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D11/00—Solvent extraction
    • B01D11/02—Solvent extraction of solids
    • B01D11/0203—Solvent extraction of solids with a supercritical fluid
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F6/00—Post-polymerisation treatments
    • C08F6/26—Treatment of polymers prepared in bulk also solid polymers or polymer melts
    • C08F6/28—Purification
    • 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
    • C08G2/00—Addition polymers of aldehydes or cyclic oligomers thereof or of ketones; Addition copolymers thereof with less than 50 molar percent of other substances
    • C08G2/28—Post-polymerisation treatments
    • 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
    • C08G85/00—General processes for preparing compounds provided for in this subclass
    • C08G85/002—Post-polymerisation treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
    • C08J2325/02—Homopolymers or copolymers of hydrocarbons
    • C08J2325/04—Homopolymers or copolymers of styrene
    • C08J2325/06—Polystyrene
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Abstract

The invention relates to a process for the purification of polymers by reducing the content of low-molecular-weight products by treating the polymer with a gas in the supercritical stage as extractant. In particular in the case of poly(meth)acrylamides, the process according to the invention offers a number of advantages.

Description

Verfahren zur Reinigung von PolymerenProcess for purifying polymers

Rückstände von Monomeren, Oligomeren, Wasser, Lösemitteln, Polymerisationsrückständen, Nebenprodukten udgl. in Polymeren können in vielerlei Hinsicht zu Problemen bei deren Verarbeitung oder Anwendung führen. Besonders bei Polymeren, die als Verpackungsmaterial dienen, wie z.B. Polystyrol, Polyvinylchlorid oder Polyolefinen, oder die im medizinischen bzw. Hygiene-Sektor eingesetzt werden, wie z.B. bei Poly(meth)acrylamiden, muß aus physiologischen Gründen darauf geachtet werden, daß der Gehalt der Polymeren an niedermolekularen Produkten, insbesondere Monomeren, möglichst gering ist.Residues of monomers, oligomers, water, solvents, polymerization residues, By-products and the like in polymers can contribute to problems in many ways conduct their processing or application. Especially with polymers that are used as packaging material such as polystyrene, polyvinyl chloride or polyolefins, or those used in medical or hygiene sector, such as with poly (meth) acrylamides, must be taken out For physiological reasons, care should be taken that the content of the polymers low molecular weight products, especially monomers, is as low as possible.

Ublicherweise wird der Anteil an niedermolekularen Verbindungen in Polymeren vermindert durch Schmelzentgasung in Schnecken-Vc rdarnpfcrn bzw. Extrudern, Entspannungsentgasung in Flash-Verdampfern, Entgasung In normalen oder IIoehviskos-Dünnschicht-Verdampfern, Behandlung mit Lösemitteln bzw.Usually, the proportion of low molecular weight compounds in Polymers reduced by degassing the melt in screw feeders or extruders, Relaxation degassing in flash evaporators, degassing in normal or low viscosity thin-film evaporators, Treatment with solvents or

Wasserdampf, z.B. in Siebboden-Kolonnen, oder durch Entgasung durch Lagerung in Lagersilos.Water vapor, e.g. in sieve tray columns, or through degassing Storage in storage silos.

Manche Polymere, z.B. Poly(meth)acrylamide, lassen sich nach allen diesen Verfahren jedoch nicht befriedigend entmonofrisieren, insbesondere weil sie bei erhöhten Temperaturen depolymerisieren und damit laufend das unerwünschte Monomere zurückgebildet wird. Prinzipiell kann zwar beispielsweise das monomere (Meth)acrylamid mit Wasser aus dem Poly(meth)-acrylamid herausgelöst werden; bei dem nachfolgenden Trocknungsprozeß, der mindestens Temperaturen von 600C erfordert, entsteht aber immer wieder (eth)acrylamid. Daher kann man nach bekannten Verfahren ein trockenes, monomerfreies Poly(meth)acrylarrid erhalten.Some polymers, e.g. poly (meth) acrylamides, can be classified according to all however, these processes do not demonofreeze satisfactorily, in particular because they depolymerize at elevated temperatures and thus continuously the undesired monomers is regressed. In principle, for example, the monomeric (meth) acrylamide be dissolved out of the poly (meth) acrylamide with water; in the following However, a drying process that requires temperatures of at least 600C occurs again and again (eth) acrylamide. Therefore one can use known methods a dry, monomer-free poly (meth) acrylarrid obtained.

Manche der oben erwähnten Methoden sind außerdem mit einem hohen Aufwand verbunden. So müssen z.B. teure Extruder mit Entgasungsdömen eingesetzt werden. Wegen der hohen EntgaS sungstemperatur sowie zur Lösemittelrückgewinnung benofngt man große Dampfmengen. Alternativ muß ein großer Siloraum zur Verfügung gestellt werden.In addition, some of the methods mentioned above require a lot of effort tied together. For example, expensive extruders have to be included Degassing dome used will. Because of the high degassing temperature and for solvent recovery large amounts of steam are required. Alternatively, a large silo must be available be asked.

Es bestand daher erfindungsgemäß die Aufgabe, ein wirkungsvolles, wenig aufwendiges Reinigungsverfahren für Polymere bereitzustellen, mit dem sich eine ausreichende Verminderung des Gehaltes an niedermolekularen Produkten, insbesondere Rest-Monomeren erreichen läßt.It was therefore the task of the invention to provide an effective, Provide little costly cleaning process for polymers, with the a sufficient reduction in the content of low molecular weight products, in particular Can achieve residual monomers.

Zur Lösung dieser Aufgabe schlägt die Erfindung ein Verfahren zur Reinigung von Polymeren durch Verminderung des Gehaltes an niedermolekularen Produkten durch Behandlung des Polymeren mit einem Extraktionsmittel vor, das dadurch- gekennzeichnet ist, daß das Extraktionsmittel ein Gas im überkritischen Zustand darstellt.To solve this problem, the invention proposes a method for Purification of polymers by reducing the content of low molecular weight products by treating the polymer with an extractant before, which is characterized is that the extractant is a gas in the supercritical state.

Die Verfahrensweise der überkritischen Extraktion ist zwar bereits seit längerem bekannt und wird besonders für thermisch empfindliche und schwerflüchtige organische Stoffe eingesetzt, wie z.B. zur Gewinnung von Pflanz-enfetten und -ölen (DE-PS 2.127.596), zur Extraktion von Wirkstoffen aus Tabak (DE-PS 2.043.537), Hopfen (DE-PS 2.127.618) und Kaffee (DE-PS 2.005.293) sowie zum Regenerieren von polymeren Adsorptionsmitteln (DE-OS 2 716 797) oder zur Entasphaltierung von Erdöl (vgl. hierzu auch Chem..lng.-Techn. 53 (1981), Nr.The supercritical extraction procedure is true known for a long time and is especially used for thermally sensitive and non-volatile products Organic substances are used, e.g. for the extraction of vegetable fats and oils (DE-PS 2.127.596), for the extraction of active ingredients from tobacco (DE-PS 2.043.537), hops (DE-PS 2.127.618) and coffee (DE-PS 2.005.293) and for the regeneration of polymers Adsorbents (DE-OS 2 716 797) or for deasphalting petroleum (cf. in this regard also Chem..lng.-Techn. 53 (1981), no.

7, S. 529 ff). Es war jedoch nicht vorhersehbar und ist als überraschend anzusehen, daß dieses Verfahren bei Polymeren so effektiv ist und daß dabei in der Regel mehrere niedermolekulare Verunreinigungen wie beispielsweise Rest-Monomere und Wasser gleichzeitig entfernt werden können. Insbesondere gilt dies bei Poly(meth)acrylamiden als Polymere.7, p. 529 ff). However, it was unpredictable and is as surprising to see that this method is so effective with polymers and that it is in the Usually several low molecular weight impurities such as residual monomers and water can be removed at the same time. This applies in particular to poly (meth) acrylamides than polymers.

Grundsätzlich ist das erfindungsgetnäP>e Verfahren auf alle Polymeren anwendbar, sofern diese mit dem überkritischen Extraktionsmittel nicht reagieren. Beispielsweise seien hier genannt: Polyoxymethylen, Polystyrol, PVC, Polyolefine wie Polyethylen und Polypropylen, Poly(meth)acrylate udgl. So lassen sich erfindungsgemäß aus Polyoxymethylen Formaldehyd, Trioxan und Tetroxan, aus Polystyrol monomeres Styrol und Reste des organischen Schäumungsmittels und aus Polyethylen bzw. Polypropylen Rest-Monomeres, niedermolekulare Oligomere und Katalysatorreste weitgehend extrahieren. Mit besonderem Vorteil kommt das erfindungsgemäße Verfahren jedoch bei Poly(meth)acrylamid zum Einsatz, wo überraschenderweise die gleichzeitige Entfernung von monomerem (Meth)Acrylamid und Wasser möglich ist. Auch bei Polystyrol, wo Monomeres, Nebenprodukte und Schäumungsmittel gleichzeitig entfernt werden können, bietet das erfindungsgemäße Verfahren erhebliche Vorteile.In principle, the process according to the invention applies to all polymers applicable provided they do not react with the supercritical extractant. For example, be here called: polyoxymethylene, polystyrene, PVC, polyolefins such as polyethylene and polypropylene, poly (meth) acrylates and the like. Let it be according to the invention from polyoxymethylene formaldehyde, trioxane and tetroxane Polystyrene monomeric styrene and residues of the organic foaming agent and off Polyethylene or polypropylene residual monomer, low molecular weight oligomers and catalyst residues extract largely. The method according to the invention is particularly advantageous however, with poly (meth) acrylamide used where, surprisingly, the simultaneous Removal of monomeric (meth) acrylamide and water is possible. Even with polystyrene, where monomers, by-products and foaming agents can be removed at the same time, the method according to the invention offers considerable advantages.

Als niedermolekulare Produkte, die erfindungsgemäß entfernt werden können, kommen neben den erwähnten Rest-Monomeren, Oligomeren, Katalysatorresten und Wasser auch Lösemittelt reste sowie andere Nebenprodukte bzw. Polymerisationsrückstände in Betracht, wobei - sofern vorhanden - durch geeignete Verfahrensführung, wie z. B. abgestufte Extraktionsdrücke, entweder alle oder zumindest die meisten dieser Verunreinigungen gleichzeitig entfernt werden können oder auch gezielt nur einige.As low molecular weight products that are removed according to the invention can come in addition to the residual monomers, oligomers and catalyst residues mentioned and water also solvent residues and other by-products or polymerization residues into consideration, where - if available - by suitable process management, such as. B. graduated extraction pressures, either all or at least most of these Impurities can be removed at the same time or just a few in a targeted manner.

Das Extraktionsmittel soll sich erfindungsgemäß im überkritischen Zustand befinden. Dabei können als Extraktionsmittel die hierfür bekannten Verbindungen - ggf. als Gemische - eingesetzt werden, wie aliphatische Kohlenwasserstoffe mit beispielsweise 1 bis 6 Kohlenstoffatomen, Ethylen, Ethan, Propan oder Propen, halogenhaltige Kohlenwasserstoffe, wie Trifluormethan, Chlordifluormethan, Chlortrifluormethan, Dichlordifluormethan oder Bromtrifluormethan. Auch Kohlendioxid, Schwefelhexafluorid oder Distickstoffoxid können hierzu verwendet werden. Besonders fiir Polymere, die für den Lebensmittelsektor bestimmt sind, kommen bevorzugt gesundheitlich unbedenkliche Extraktionsmittel, wie Kohlendioxid in Betracht. Gegebenenfalls können auch zusätzliche als sogenannte Schleppmittel dienende Medien wie Methanol, Ethanol, Dimethylformamid, Aceton, Acetonitril, Benzol, Toluol, udgl. mitverwendet werden.According to the invention, the extractant should be supercritical Condition. The compounds known for this purpose can be used as extractants - possibly as mixtures - are used, such as aliphatic hydrocarbons with for example 1 to 6 carbon atoms, ethylene, ethane, propane or propene, halogen-containing Hydrocarbons such as trifluoromethane, chlorodifluoromethane, chlorotrifluoromethane, Dichlorodifluoromethane or bromotrifluoromethane. Also carbon dioxide, sulfur hexafluoride or nitrous oxide can be used for this purpose. Especially for polymers that intended for the food sector, preference is given to those that are harmless to health Extracting agents, such as carbon dioxide, can be considered. If necessary, additional as so-called entrainer media such as methanol, ethanol, dimethylformamide, Acetone, acetonitrile, benzene, toluene, etc. can also be used.

Zur Herbeiführung des überkritischen Zustandes liegen die Temperatur und der Druck, unter denen das erfindungsgemäße Verfahren durchgeführt wird, mindestens bei der kritischen Temperatur bzw. beim kritischen Druck des jeweiligen Extraktionsmittels, vorzugsweise jedoch darüber. Im allgemeinen sind Temperaturen zwischen der kritischen Temperatur und 20000, vorzugsweise 12000 möglich. Besonders bevorzugt liegen die Temperaturen zwischen 500 und 7000 oberhalb der kritischen Temperatur. Die entsprechenden Drücke liegen zwischen dem kritischen Druck und 1000 bar, vorzugsweise 400 bar und insbesondere zwischen 30 bar und 300 bar ober halb des kritischen Druckes.The temperature is used to bring about the supercritical state and the pressure under which the process according to the invention is carried out, at least at the critical temperature or at the critical pressure of the respective extractant, but preferably above. In general, temperatures are between the critical ones Temperature and 20,000, preferably 12,000 possible. Particularly preferred are the Temperatures between 500 and 7000 above the critical temperature. The corresponding Pressures are between the critical pressure and 1000 bar, preferably 400 bar and in particular between 30 bar and 300 bar above half the critical pressure.

Die Durchführung des erfindungsgemäßen Verfahrens erfolgt in der üblichen Weise, wobei das Extraktionsmittel vorzugsweise im Kreislauf geführt wird und die Abscheidung der darin gee lösten Stoffe vorzugsweIse durch Absenkung des Druckes bzw.The method according to the invention is carried out in the customary manner Way, wherein the extractant is preferably circulated and the Separation of the substances dissolved therein, preferably by lowering the pressure respectively.

durch Absenkung oder Erhöhung der Temperatur erfolgt (vgl.takes place by lowering or increasing the temperature (cf.

hierzu beispielsweise die DE-OS 1.lot93.190 und Ohem.-Ing.-Techn. 53 (1981), Nr. 7, S. 529 off). Da im Verlauf der Extraktion oft die Beladung des Lösemittels abnimmt, die Lösefähigkeit des Lösemittels also nicht mehr vollständig ausgenutzt wird, kann nach Unterschreiten der maximalen Beladung um z. B. 10 % das teilweise beladene Lösemittel auch zusätzlich durch einen zweiten mit frischem Extraktionsgut gefüllten Extraktionsbehälter geleitet werden.for example DE-OS 1.lot93.190 and Ohem.-Ing.-Techn. 53 (1981), No. 7, p. 529 off). Since the loading of the Solvent decreases, so the solvency of the solvent is no longer complete is used, after falling below the maximum load by z. B. 10% that partially loaded solvents also with a second one with fresh extraction material filled extraction vessel.

Eine bevorzugte Ausführungsform des erfindungsgcmäßen Verfahrens wird nachfolgend anhand der beigefügten Figur näher -beschrieben: Der Extraktionsbehälter (), der gegebenenfalls mit Siebbodeneinsätzen versehen ist, wird mit dem feinteiligen Polymeren beschickt. Nach dem Entfernen des Luftsauerstoffs durch Spülen der ganzen Anlage mit Kohlendioxid wird der Behälter (1) sowie der Entmischungsbehälter (3) aus dem Tank (7) mit dem Extraktionsmittel gefüllt. Dieses wird in dem auf Extraktionstemperatur thermostatisierten Behälter (1) weiter auf den Extraktionsdruck komprimiert. Dabei belädt sich das überkritische Medium mit den niedermolekularen Verbindungen im Sinne einer "überkritischen Lösung« Der Gasstrom wird dann durch den Wärmeaustauscher (2) in den Behälter (3) überführt und dort entmischt. Dies erfolgt vorzugsweise durch Absenken des Drucks auf Werte unterhalb des kritischen Drucks des Gases. Die Temperatur kann hierbei ebenfalls auf unterkritische Werte gesenkt, aber auch auf der gleichen Höhe wie im Extraktionsbehälter (1) belassen oder sogar erhöht werden. Der om Extrakt befreite Gasstrom wird aus dem Behälter (3) durch den Wärmeaustauscher (4) in die Flüssiggaspumpe bzw. den Kompressor (5) geleitet, dort komprimiert und durch den Wärmeaustauscher (6) wieder in den Extraktionsbehälter (1) gefördert. Damit ist der Kreislauf des Extraktionsmittels geschlossen.A preferred embodiment of the method according to the invention is described in more detail below with reference to the attached figure: The extraction container (), which is optionally provided with sieve bottom inserts, is mixed with the finely divided Loaded with polymers. After removing the oxygen in the air by The tank (1) and the separation tank are rinsed with carbon dioxide throughout the entire system (3) Filled with the extractant from the tank (7). This is in the extraction temperature thermostated container (1) is further compressed to the extraction pressure. Included loads the supercritical medium with the low molecular weight compounds in the sense a "supercritical solution" The gas flow is then through the heat exchanger (2) transferred to the container (3) and segregated there. This is preferably done by lowering the pressure to values below the critical pressure of the gas. the The temperature can also be reduced to subcritical values, but also to can be left at the same height as in the extraction container (1) or even increased. The gas stream freed from the extract is from the container (3) through the heat exchanger (4) into the liquid gas pump or the compressor (5), where it is compressed and conveyed through the heat exchanger (6) back into the extraction container (1). This completes the extraction agent cycle.

Zur Minimierung des Energieverbrauehs werden sinnvollerweise die Wärmeaustauscher miteinander kombiniert. Weiter hin wird man vor dem öffnen der Anlage nach beendeter Extraktion das Gas so weit wie möglich durch Abpumpen und Wiederverflüssigung zurückgewinnen. Einen Teil des Hochdruckgases kann man auch dazu verwenden, einen zum Behälter (1) parallelgeschalteten zweiten Extraktionsbehälter teilweise mit Gas zu füllen.In order to minimize the energy consumption, it makes sense to use the heat exchangers combined with each other. You will continue to go before opening the system after it has finished Extract the gas to recover as much as possible by pumping it down and reliquefying it. Part of the high-pressure gas can also be used to direct one to the container (1) to partially fill the second extraction vessel connected in parallel with gas.

In den folgenden Beispielen bedeuten P1 und P2 den Extraktions- bzw. Entmischungsdruck und T1 und T2 die Extraktions- bzw. Entmischungstcmperatur.In the following examples, P1 and P2 mean the extraction or Separation pressure and T1 and T2 the extraction or separation temperature.

Beispiel 1 100 g eines feinkörnigen Polyethylens (LDPE) wurden in der Apparatur g;einäS Figur wie folgt behandelt: Lösemittel: 3,1 kg C02/h P1= 300 bar T 0°C Dauer: 5h P2= 50 bar, T2=22°C Der niedermolekulare Anteil mit einer Molmasse bis 1000 hai von 0,6 % auf 0,27 % abgenommen.Example 1 100 g of a fine-grained polyethylene (LDPE) were in the apparatus g; a figure treated as follows: Solvent: 3.1 kg C02 / h P1 = 300 bar T 0 ° C Duration: 5h P2 = 50 bar, T2 = 22 ° C The low molecular weight part with a molar mass up to 1000 hai decreased from 0.6% to 0.27%.

Beispiel 2 100 g eines expandierbaren Po]ystyrols mit einem Teilchendurchmesser von 0,3 - 0,5 mm wurden in der Apparatur gemäß Figur wie folgt behandelt: Lösemittel: 3 kg C02/h P1= 300 bar, T1= 14000 Dauer: 5 h 2= 50 bar, T2 = 2100 Der Gehalt an monomerem Styrol wurde von anfänglich 50 ppm auf weniger als 50 ppm vermindert. Ebenfalls auf weniger als 50 ppm verringerte sich der Gehalt n Ethylbenzol (vnn 300 ppm), an n-Propylbenzol (von 150 ppm) und an iso-Propylbenzol (von 250 ppm). Gleichzeitig nahnien die Verdampfungsverluste (hauptsächlich Schäumungsmittel) nach 1 h bei 140°C von 3,94 % auf 0.33 P ab.Example 2 100 g of an expandable polystyrene with a particle diameter from 0.3-0.5 mm were treated as follows in the apparatus according to the figure: Solvent: 3 kg C02 / h P1 = 300 bar, T1 = 14000 Duration: 5 h 2 = 50 bar, T2 = 2100 The content of monomeric styrene was reduced from an initial 50 ppm to less than 50 ppm. The content n ethylbenzene (vnn 300 ppm), n-propylbenzene (from 150 ppm) and iso-propylbenzene (from 250 ppm). At the same time, the evaporation losses (mainly foaming agents) follow suit 1 h at 140 ° C from 3.94% to 0.33 P.

Beispiel 3 70 g eines in etwa 1 mm große Teilchen zerkleinerten gelförmigen Acrylamidcopolymerisats wurden in der Apparatur gemäß Figur wie folgt behandelt: Lösemittel: 3 kg C02/h P1= 150 bar, T1= 120°C Dauer: 2 h P2= 50 bar, T2= 25°C Es wurden 87 % des Wassers entfernt. Der Feststoff-Gehalt stieg dadurch von anfarlg; 30 % auf 7G % an.Example 3 70 g of a gel-shaped particle comminuted into approximately 1 mm large particles Acrylamide copolymers were treated in the apparatus according to the figure as follows: Solvent: 3 kg C02 / h P1 = 150 bar, T1 = 120 ° C Duration: 2 h P2 = 50 bar, T2 = 25 ° C Es 87% of the water was removed. As a result, the solids content rose from initial; 30% to 7G%.

Beispiel 4 80 g eines auf 74 % Feststoff-Gehalt getrockneten, teilhydrolysierten Polyacrylamid-Granulats (0,3 -1 mm Teilchengröße) wurden in der Apparatur gemäß Figur wie folgt behandelt: Lösemittel: 1,6 kg jthylen/h P1= 300 bar, T 1= 4000 Dauer: 5 h P2= 50 bar, T2= 500 Der aufängliche Gehalt an monomeren Aerylamid war von 165 ppm auf 50 ppm vermindert worden. Gleichzeitig stieg der Feststoffgehalt auf 76 % an.Example 4 80 g of a partially hydrolyzed product which has been dried to a solids content of 74% Polyacrylamide granules (0.3-1 mm particle size) were in the apparatus according to Figure treated as follows: Solvent: 1.6 kg ethylene / h P1 = 300 bar, T 1 = 4000 Duration: 5 h P2 = 50 bar, T2 = 500 The acceptable content of monomeric aerylamide was 165 ppm has been reduced to 50 ppm. At the same time the solids content rose to 76 % at.

Beispiel 5 100 g eines Polyoxyrnethylen-Pulvers (Teilchengröße < 0,1 mm; Molekulargewicht ca. 3000; MFI= 9) wurden in der Apparatur gemäß Figur wie folgt behandelt: Lösemittel: 3,6 kg CO2/h P1= 300 bar, T 1= 80°C Dauer: 5 h P2= 50 bar, T2= 22°C Der Gehlat an Formaldehyd verminderte sich von anfangs 170 ppm auf 125 ppm. Oleichzeitig nahm der Gehalt an Trioxan/Tetroxan von 230 ppm auf 65 pprrl al.Example 5 100 g of a polyoxyethylene powder (particle size < 0.1 mm; Molecular weight approx. 3000; MFI = 9) were in the apparatus according to FIG treated as follows: Solvent: 3.6 kg CO2 / h P1 = 300 bar, T 1 = 80 ° C Duration: 5 h P2 = 50 bar, T2 = 22 ° C. The formaldehyde content decreased from 170 ppm at the beginning to 125 ppm. At the same time, the trioxane / tetroxane content increased from 230 ppm to 65 pprrl al.

Beispiel 6 100 g eines fein verteilten Polypropylen-Wachses wurden in der Apparatur gemciß Figur wie folgt behandelt: Lösemittel: 3,1 kg CO2/h P1= 300 bar, T1= 60°C Dauer: 5 h P2= 55 bar, T2= 22°C Der Anteil an flüchtigen Verbindungen (Propylen und RVarsol) hahm von anfange 1,3 % auf 0,08 % ab. Gleichzeitig verminderte sich der Oligomer-Gehalt (Molmasse bis 1000 g/mol) von anfänglich 1,31 % auf 0.35 7.Example 6 100 g of a finely divided polypropylene wax was made treated in the apparatus according to the figure as follows: Solvent: 3.1 kg CO2 / h P1 = 300 bar, T1 = 60 ° C Duration: 5 h P2 = 55 bar, T2 = 22 ° C The proportion of volatile compounds (Propylene and RVarsol) decreased from an initial 1.3% to 0.08%. At the same time decreased the oligomer content (molar mass up to 1000 g / mol) from an initial 1.31% to 0.35 7th

Claims (6)

Patentansprüche: (1 Verfahren zur Reinigung von Polymeren durch Verminderung des Gehaltes an niedermolekularen Produkten durch Behandlung des Polymeren mit einem xtraktionsmittel, dadurch gekennzeichnet, daß das Extraktionsmittel ein Gas im überkritischen Zustand darstellt.Claims: (1 process for the purification of polymers by reduction the content of low molecular weight products by treating the polymer with a extraction agent, characterized in that the extraction agent is a gas in the supercritical State represents. 2. Verfahren nach Anspruch 1, dadurch gekennzeIchnet, daß die Temperatur zwischen (oberhalb) der überkritischen Temperatur des betreffenden Fluids und 2000C, in.besondere 1200C, liegt.2. The method according to claim 1, characterized in that the temperature between (above) the supercritical temperature of the fluid in question and 2000C, in particular 1200C. 3. Verfahren nach den Ansprüchen 1 und 2, dadurch gekennzeichnet, daß auch der Druck zwischen (oberhalb) dem kritischen Druck des betreffenden Fluids und 1000 bar, insbesondere 400 bar, liegt.3. The method according to claims 1 and 2, characterized in that that also the pressure between (above) the critical pressure of the fluid in question and 1000 bar, in particular 400 bar. h. Verfahren nach den Ansprüchen 1 bis 3, dadurch gekennzeichnet, daß das Polymere ein Poly(meth)acrylainid ist.H. Process according to Claims 1 to 3, characterized in that that the polymer is a poly (meth) acrylamide. 5. Verfahren nach den Ansprüchen 1 bis 4, dadurch gekennzeichnet, daß als überkritisches Fluid ein aliphatischer Kohlenwasserstoff mit 1 bis 6 Kohlenstoffatomen, ein halogenierter Kohlenwasserstoff, Kohlendioxid, Schwefelhexafluorid oder Distickstoffoxid einzeln oder im Gemisch verwendet wird.5. Process according to claims 1 to 4, characterized in that that the supercritical fluid is an aliphatic hydrocarbon with 1 to 6 carbon atoms, a halogenated hydrocarbon, carbon dioxide, sulfur hexafluoride or nitrous oxide is used individually or in a mixture. 6. Verfahren nach den Ansprüchen 1 bis 5, dadurch gekennzeichnet, daß man das überkritische Fluid im Kreislauf führt - ggfs. durch mehrere hintereinandergeschaltete Extraktionsbehälter - und die gelösten Stoffe durch Absenkung des Druckes bzw. durch Absenkung oder Erhöhung der Temperatur abscheidet.6. The method according to claims 1 to 5, characterized in that that the supercritical fluid is circulated - possibly through several series-connected Extraction tank - and the dissolved substances by lowering the pressure or by Lowering or increasing the temperature is deposited.
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EP0233661A1 (en) * 1986-01-23 1987-08-26 Stamicarbon B.V. Process for purifying a thermoplastic polymer
US4695621A (en) * 1985-12-23 1987-09-22 The Dow Chemical Company Method for reducing residual monomers from oversized fat imbibing copolymer beads
US4703105A (en) * 1985-12-23 1987-10-27 The Dow Chemical Company Extraction of residues from styrenic polymers
EP0269583A2 (en) * 1986-11-21 1988-06-01 COBARR S.p.A. A method for producing high molecular weight polyester resin
FR2611207A1 (en) * 1987-02-19 1988-08-26 Rhone Poulenc Sante PROCESS FOR THE PURIFICATION OF STYRENE COPOLYMERS WITH VINYLPYRIDINES BY EXTRACTION USING SUPERCRITICAL GAS
EP0289132A1 (en) * 1987-03-27 1988-11-02 Asahi Denka Kogyo Kabushiki Kaisha Method of removing solvent from chlorinated resin
EP0300981A1 (en) * 1987-07-24 1989-01-25 COBARR S.p.A. A method for the reduction of impurities in polyester resins
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FR2641198A1 (en) * 1988-10-26 1990-07-06 Toyo Engineering Corp Process for extracting impurities present in a material in the form of powder II
EP0435328A2 (en) * 1989-12-28 1991-07-03 Dow Corning Toray Silicone Company, Limited Method for reducing the quantity of siloxane oligomer in organopolysiloxane moldings
EP0442679A1 (en) * 1990-02-16 1991-08-21 Rohm And Haas Company Purification of latex
US5049328A (en) * 1990-07-02 1991-09-17 Arco Chemical Technology, Inc. Purification, impregnation and foaming of polymer particles with carbon dioxide
EP0456246A2 (en) * 1990-05-10 1991-11-13 Boehringer Ingelheim Kg Process for manufacturing solventless/residual monomerless polymers, to be used in processes such as injection, extrusion or meltspinning
DE4120437A1 (en) * 1990-06-21 1992-01-09 Toyo Engineering Corp METHOD FOR THE EXTRACTION OF IMPURITIES IN A POLYMER DISPERSION
US5094741A (en) * 1990-03-02 1992-03-10 Hewlett-Packard Company Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
WO1993003064A1 (en) * 1991-07-29 1993-02-18 M. & G. Ricerche S.P.A. Process for the separation of the aqueous phase from cellulose acetate
US5232707A (en) * 1989-07-10 1993-08-03 Syntex (U.S.A.) Inc. Solvent extraction process
US5240603A (en) * 1990-03-02 1993-08-31 Hewlett-Packard Company Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
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WO1995018834A1 (en) * 1994-01-07 1995-07-13 Minnesota Mining And Manufacturing Company Supercritical fluid extraction involving hydrofluoroalkanes
US5569510A (en) * 1992-06-10 1996-10-29 Sinco Engineering S.P.A. Process for the production of polyester resins for fibers
WO1997005194A1 (en) * 1995-08-01 1997-02-13 Cf Technologies, Incorporated Method and apparatus for separating polymer from a plastic, and the resulting separated polymer
WO1997020866A1 (en) * 1995-12-04 1997-06-12 Basf Aktiengesellschaft Process for the removal of residual solvents and residual monomers from powdered polymerisates
WO1997034334A1 (en) * 1996-03-15 1997-09-18 Valence Technology, Inc. Apparatus and method of preparing electrochemical cells
WO1997040081A1 (en) * 1996-04-23 1997-10-30 Joachim Brimmer Ingenieurbüro Anlagenbau Gmbh Process for separating organic monomers or auxiliaries
US6160086A (en) * 1998-07-30 2000-12-12 3M Innovative Properties Company Process for removing impurities from polymers
US6180031B1 (en) * 1994-01-31 2001-01-30 Bausch & Lomb Incorporated Treatment of contact lenses with supercritical fluid
EP1467854A1 (en) * 2001-12-12 2004-10-20 Depuy Products, Inc. Orthopaedic device and method for making same
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US4695621A (en) * 1985-12-23 1987-09-22 The Dow Chemical Company Method for reducing residual monomers from oversized fat imbibing copolymer beads
US4703105A (en) * 1985-12-23 1987-10-27 The Dow Chemical Company Extraction of residues from styrenic polymers
EP0233661A1 (en) * 1986-01-23 1987-08-26 Stamicarbon B.V. Process for purifying a thermoplastic polymer
EP0269583A3 (en) * 1986-11-21 1990-01-31 Cobarr S.P.A. A method for producing high molecular weight polyester resin
EP0269583A2 (en) * 1986-11-21 1988-06-01 COBARR S.p.A. A method for producing high molecular weight polyester resin
EP0281464A1 (en) * 1987-02-19 1988-09-07 Rhone-Poulenc Sante Process for the purification of styrene-vinyl pyridine copolymers by extraction, using a supercritical gas
FR2611207A1 (en) * 1987-02-19 1988-08-26 Rhone Poulenc Sante PROCESS FOR THE PURIFICATION OF STYRENE COPOLYMERS WITH VINYLPYRIDINES BY EXTRACTION USING SUPERCRITICAL GAS
EP0289132A1 (en) * 1987-03-27 1988-11-02 Asahi Denka Kogyo Kabushiki Kaisha Method of removing solvent from chlorinated resin
EP0300981A1 (en) * 1987-07-24 1989-01-25 COBARR S.p.A. A method for the reduction of impurities in polyester resins
EP0322687A2 (en) * 1987-12-28 1989-07-05 Schwarz Pharma Ag Method for the manufacture of a product having at least one substance embedded in a carrier
EP0322687A3 (en) * 1987-12-28 1990-04-11 Schwarz Pharma Ag Method for the manufacture of a product having at least one substance embedded in a carrier
EP0334314A3 (en) * 1988-03-23 1990-07-25 Mitsubishi Gas Chemical Company, Inc. Method for producing purified polycarbonate resins
EP0334314A2 (en) * 1988-03-23 1989-09-27 Mitsubishi Gas Chemical Company, Inc. Method for producing purified polycarbonate resins
FR2638098A1 (en) * 1988-10-26 1990-04-27 Toyo Engineering Corp PROCESS FOR EXTRACTING IMPURITIES CONTAINED IN POWDER MATERIAL
FR2641198A1 (en) * 1988-10-26 1990-07-06 Toyo Engineering Corp Process for extracting impurities present in a material in the form of powder II
EP0376064A2 (en) * 1988-12-15 1990-07-04 Toyo Engineering Corporation Method for producing a foamed resin
EP0376064A3 (en) * 1988-12-15 1990-12-05 Toyo Engineering Corporation Method for producing a foamed resin
US5133913A (en) * 1988-12-15 1992-07-28 Toyo Engineering Corporation Method for producing a foamed resin using a blowing and extracting agent
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EP0374879A3 (en) * 1988-12-23 1991-08-14 Toyo Engineering Corporation Method for extraction of impurities in polymer
US5232707A (en) * 1989-07-10 1993-08-03 Syntex (U.S.A.) Inc. Solvent extraction process
US5167883A (en) * 1989-12-28 1992-12-01 Dow Corning Toray Silicone Company, Ltd. Method for reducing the quantity of siloxane oligomer in organopolysiloxane moldings
EP0435328A3 (en) * 1989-12-28 1991-11-06 Dow Corning Toray Silicone Company, Limited Method for reducing the quantity of siloxane oligomer in organopolysiloxane moldings
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US5322626A (en) * 1990-03-02 1994-06-21 Hewlett-Packard Company Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
US5094741A (en) * 1990-03-02 1992-03-10 Hewlett-Packard Company Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
US5240603A (en) * 1990-03-02 1993-08-31 Hewlett-Packard Company Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
EP0456246A2 (en) * 1990-05-10 1991-11-13 Boehringer Ingelheim Kg Process for manufacturing solventless/residual monomerless polymers, to be used in processes such as injection, extrusion or meltspinning
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EP0467551A2 (en) * 1990-07-02 1992-01-22 ARCO Chemical Technology, L.P. Purification, impregnation and foaming of polymer particles
EP0467551A3 (en) * 1990-07-02 1992-06-17 Arco Chemical Technology Inc. Purification, impregnation and foaming of polymer particles
US5049328A (en) * 1990-07-02 1991-09-17 Arco Chemical Technology, Inc. Purification, impregnation and foaming of polymer particles with carbon dioxide
US5667691A (en) * 1991-07-29 1997-09-16 Sinco Engineering S.P.A. Process for extracting water and acetic acid from the aqueous phase of cellulose acetate
WO1993003064A1 (en) * 1991-07-29 1993-02-18 M. & G. Ricerche S.P.A. Process for the separation of the aqueous phase from cellulose acetate
US5569510A (en) * 1992-06-10 1996-10-29 Sinco Engineering S.P.A. Process for the production of polyester resins for fibers
WO1995018834A1 (en) * 1994-01-07 1995-07-13 Minnesota Mining And Manufacturing Company Supercritical fluid extraction involving hydrofluoroalkanes
US5481058A (en) * 1994-01-07 1996-01-02 Minnesota Mining And Manufacturing Company Supercritical fluid extraction involving hydrofluoroalkanes
US6610221B2 (en) 1994-01-31 2003-08-26 Bausch & Lomb Incorporated Treatment of contact lenses with supercritical fluid
US6180031B1 (en) * 1994-01-31 2001-01-30 Bausch & Lomb Incorporated Treatment of contact lenses with supercritical fluid
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US5739270A (en) * 1995-08-01 1998-04-14 Farmer; Peter H. Method and apparatus for separating polymer from a plastic, and the resulting separated polymer
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US5961671A (en) * 1996-03-15 1999-10-05 Valence Technology, Inc. Apparatus and method of preparing electrochemical cells
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WO2006023129A1 (en) * 2004-08-05 2006-03-02 Mallinckrodt Baker, Inc. Preparation of ultrapure polymeric articles
US7470767B2 (en) 2004-08-05 2008-12-30 Mallinckrodt Baker, Inc. Preparation of ultrapure polymeric articles
AU2005277901B2 (en) * 2004-08-05 2010-06-10 Avantor Performance Materials, Inc. Preparation of ultrapure polymeric articles
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