Innovative Process Solutions

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A Jakob Müller Company

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Main Evaporation

The high viscosity of certain polymers sometimes prevents polymerization in the concentrated phase. In these cases, the monomers must be polymerized with a large excess of suitable solvents.

Following the solution polymerization process step the low viscous polymer-solvent solution is typically pre-concentrated by flash evaporation. The solid content, to which the solution can be concentrated to, is limited by the flow ability of the viscous solution in the flash vessel.

To be able to reach higher solid concentrations the LIST KneaderReactor is the ideal and most economical technology. It allows concentrating the solution up to a solid content of 90 - 95 %.

This process is easily scalable since the heat energy needed to evaporate the solvent is mainly provided by the mechanical kneading energy. The foam generated by evaporating the low viscous polymer solution is effectively eliminated by the viscous polymer mass. Moreover, the LIST KneaderReactor allows an accurate control of the product temperature. This prevents the formation of crumbles at lower product temperatures or thermal degradation at higher product temperatures.

The subsequent process step where the Polymer is finished to its final quality is the devolatilization.

 

 

Example

Elastomers

  • Ethylene-Propylene Rubbers (EPDM)
  • Polybutadiene Rubber (BR)
  • Butyl (isobutylene isoprene) Rubber (IIR)
  • Polyisoprene Rubber (IR)
  • Solution Styrene-Butadien Rubber (S-SBR)
  • Polyolefin Elastomers (POE)
  • Acrylonitrile-Butadiene Rubber (NBR)

 

Thermoplastic Elastomers

  • Styrene block copolymers (SBS, SIS)

Your Benefits

  • Effective self-cleaning to minimize dead zones, product accumulation and product degradation
  • Excellent kneading and mixing for better homogenization
  • High input of mechanical power and kneading torque
  • Effective heat transfer
  • High surface renewal efficiency
  • Large free vapour volume
  • Precise and uniform temperature control due to large heat transfer areas
  • Continuous processing
  • Processing of sticky and highly viscous products
  • Wide and flexible range of average residence times
  • Wide range of possible residence time distributions (backmixed)
  • Reliable process scale-up from pilot to industrial units
  • Low and high Mooney type elastomers

Downloads

Titel Beschreibung Sprache Jahr Download
Direct devolatilisation in a closed system For decades, conventional polymerisation has been the norm in the production of elastomers. The time and cost involved in removing and treating solvents in the final stages of production were acceptable. Yet as pressure builds on manufacturers to reduce operating costs, there is greater urgency to develop processes that can help streamline costs and production techniques. One such effort has yielded extremely promising results. English 2015
Efficient and eco-friendly polymerization of elastomers For decades, conventional polymerization in the production of elastomers has been the norm. The time and cost involved in removing and treating solvents in the final stages of production, for example, were acceptable. But as pressure builds on manufacturers to reduce operating costs, there is greater urgency to develop processes that can help streamline cost and production. One such effort by List AG has yielded promising results. English 2014
Efficient & Easy Elastomer Processing Conventional polymerisation in the production of elastomers has been the norm for decades. The time and cost involved in removing and treating solvents in th e final stages of production , for example, were acceptable, but as pressure builds on manufacturers to reduce operating costs, there is greater urgency to develop processes that can help streamline cost and production. One such effort has yielded extremely promising results. English 2013
Continuous masterbatch process for the cellulose fiber industry The achievable final volatile content within kneader devolatilization processes is highly dependent on the final melt temperature. For thermosensitive polymers the state of the art process performs poorly. The amount of dissipated energy leads to a heat up of the polymer, limiting the maximal kneader shaft speed and therefore volatile removal rate. This new process uses a suitable additional volatile compound to cool off the dissipated energy by evaporation using the off gas to strip and boost the mass transfer coefficient. A complex multi-parameter study is presented, to predict performance of industrial equipment from pilot scale data. English 2011
New devolatilization process for thermosensitive and highly viscous polymers in high volume Kneader Reactors The achievable final volatile content within kneader devolatilization processes is highly dependent on the final melt temperature. For thermosensitive polymers the state of the art process performs poorly. The amount of dissipated energy leads to a heat up of the polymer, limiting the maximal kneader shaft speed and therefore volatile removal rate. This new process uses a suitable additional volatile compound to cool off the dissipated energy by evaporation using the off gas to strip and boost the mass transfer coefficient. A complex multi-parameter study is presented, to predict performance of industrial equipment from pilot scale data. English 2011
Kneten statt strippen Der Einsatz von großen Lösemittelmengen in Polymerisationsprozessen mit den damit verbundenen Nachteilen muss nicht sein. Ein optimiertes Verfahren ermöglicht die direkte Entgasung von Lösemitteln, ohne dabei Strippmittel einsetzen zu müssen. Aufwendige Trennschritte werden so vermieden und höhere Produktqualitäten können erreicht werden. Deutsch 2010
Schritt in eine neue Welt Der Einsatz von großen Lösungsmittelmengen in Polymerisationsprozessen mit den damit verbundenen Nachteilen muss nicht sein. Ein neues Verfahren beschreitet neue Wege: Kneten statt strippen lautet die Devise. Deutsch 2010
Predition of mass transport of solvent / polymer systems in high volume Kneader Reactors at finite solvent concentrations Kneader reactors are used for combined unitary processing in the polymer industry for devolatilization, compounding or polymerization. In the past, mass transport prediction for devolatilization operations in kneader reactors did not match experimental results, when diffusion was assumed as sole driving force. It was detected that there is an additional concentration and temperature dependent driving force that triggers enhanced transport at finite solvent concentrations by orders of magnitude. The author suggests that the underlying root cause is likely micro bubble formation within the polymer melt. An attempt to model this additional mass transport mechanism is presented. English 2008
Kneader technology for the direct devolatilitation of temperature sensitive elastomers Synthetic elastomers have been produced for over 50 years. Advances in catalyst systems and polymer formulations have been somewhat diminished by the continued use of the same processing technology. In particular, the use of coagulation, steam stripping, mechanical dewatering, and convective drying for the devolatilization of temperature sensitive elastomeric solutions can be replaced with direct devolatilization using kneader technology. A two-step, direct devolatilization process has demonstrated energy savings and advantages in environmental emissions and process/product flexibility when compared to the conventional steam stripping process. English 2008
Ohne Wasserdampf zum Kautschuk Die Synthese von Kautschuk ist ein wichtiger Prozess: Hersteller von Gummiprodukten - ganz gleich ob Autoreifen oder Kondome - benötigen hochwertigen Kautschuk als Ausgangswerkstoff. Doch die Kautschukerzeugung ist teuer und verschlingt große Mengen an Energie. Forschern des Fraunhofer-Instituts für Angewandte Polymerforschung IAP in Potsdam ist es gemeinsam mit ihren Entwicklungspartnern LIST AG und Dow Olefinverbund GmbH gelungen, den Energiebedarf der Kautschuksynthese um 76 Prozent zu senken. Deutsch 2007
Somethin special in separation technology The synthesis of most elastomers is carried out either by Solution or emulsion polymerization. After the polymcrization step, the polymer is separated from the solvent or emulsifying agents. This separation requires several process steps including coagulation, Stripping, various mechanical separation stages, and finally diying. Beyond that, the existing technologies are energy consuming, waste solvent must be incinerated, and the installation of main and ancillaiy equipment occupies large spaces. English 2007
Torque and speed fluctuation on polymer processing large volume kneader Large volume kneaders are designed to handle highly viscous polymer processing. The unitary operations can be compounding, polymerizations, devolatilization or drying. Depending on the polymer viscosity in the kneader, the interaction of kneading elements induce a torque and force evolution on the shaft over one revolution. English 2006
Elastomer efficiency How direct devolatisation of an elastomer solution can save time and money English 2006
Kontinuierliche Eindampfung und Entgasung von Polymerschmelzen Polymerprozesse - Aufbereitung und Finishing von Polymeren - Knetertechnologie in der Polymeraufbereitung - Wirtschaftlichkeit Deutsch 2006
Eindampfung und Entgasung von Polymerschmelzen Die bestehenden Technologien für die Aufbereitung von Polymeren nach der Polymerisation können in ein-, zwei- und mehrstufige Verfahren unterteilt werden. Dem entsprechend kommen Stripptechnologien mit nachgeschalteter mechanischer und thermischer Entfernung der Hilfsmittel, Extruder in verschiedenen Bauarten und großvolumige Kneter zum Einsatz. Die Knetertechnologie ist vor allem für temperatur- und scherempfindliche Polymermassen geeignet, bei denen die Entgasung diffusionsbestimmt ist. Deutsch 2006
Computer Berechnung des Scale up für Entgasungsvorgänge in Knetreaktoren Eine konzentrierte Elastomerlösung (weniger als 20 % Lösungsmittel) wird einem großvolumigen Knetreaktor zugeführt, um das Lösungsmittel bis auf ppmGehalte zu entfernen. Um diesen Entgasungsschritt zu beschreiben, wurde ein Simulationsprogramm entwickelt. Das Programm errechnet den Restlösungsmittelgehalt, den Füllgrad und das Drehmoment des Reaktors. Es kann sowohl der Feineinstellung sowie auch dem Scale-up des Prozesses dienen. Deutsch 2005
Leuchtturm in karger Forschungslandschaft Das Fraunhofer-Pilotanlagenzentrum für Polymersynthese und -verarbeitung Deutsch 2005
Computer scale up model for Desolventizing highly viscous polymers A concentrated rubber solution (less than 20 % solvent) is fed to a high volume kneader in order to remove the solvent down to ppm level. A simulation program has been developed to describe this devolatilization step. The program predicts final solvent content, the filling level and the mechanical torque build-up. The program can be used to refine process control and the scale-up of this type of process. English 2005
Comparison devolatilization technologies for viscous polymers Devolatilization of solvents from viscous polymer cement is realized through stripping of solvent with steam in stirred vessels or directly by evaporating the solvent from the polymer. The later so-called direct desolventizing is realized in extruders or high volume kneaders. All 3 methods involve additional energy to drive out solvent either by partial pressure through additional steam (steam stripping), building and releasing pressure in order to explode the polymer bulk (extruder) or dynamic surface renewal (kneader). English 2005
LIST im Demo Zentrum Polymersynthese Energieeinsparung und Qualitätsverbesserung durch indirekte Eindampfung von Polymerlösungen oder direkte Polymerisation und Polykondensation Deutsch 2004
Finishing reaction of PA6 in the melt phase The difference in the production of PA6 in comparison to that of other polymers is the downstream water extraction and drying after the granulation. During these process steps, the monomer and the oligomer contents in the final product are reduced in the 0.2 to 0.6 ww/w range. The installed units for extraction and drying of the final granulated product are characterized by their large energy consumption, which considerably influences manufacturing costs. English 2002