10/11/ ACS Rubber Division 180 th Technical Meeting Kneader Technology for the Direct Devolatilization of Temperature Sensitive Elastomers Boyd T. Safrit, PhD, PE Andreas E. Diener, Dipl. Ing.

10/11/2011 – p. 2 Conventional Process  Polymerization exothermic  Temperature control important  Polymer temperature sensitive  Viscosity increases with MW build   Solution polymerization  Stirred tank reactors  Steam stripping for solvent removal

10/11/2011 – p. 3 Conventional Process Solution Polymerization Stripping Separation Confectioning Coagulation Expeller Expander Belt dryer Water / steam consumption, solvent recovery Air handling and emissions Plant footprint, maintenance

10/11/2011 – p. 4 Conventional vs. Direct Devolatilization Solution Polymerization Stripping Separation Confectioning Coagulation Expeller Expander Belt dryer Main Evaporation Finishing

10/11/2011 – p. 5 Kneader Technology

10/11/2011 – p. 6 Kneader Technology

10/11/2011 – p. 7 Main Evaporation  Cement feed of 75-90% solvent  Maximum temperature of 100°C  High energy duty for solvent evaporation   Back mixed kneader reactor  Discharge target of 2-10% solvent  High mechanical energy input

10/11/2011 – p. 8 Finishing  Pasty feed of 2-10% solvent  Maximum temperature of 100°C  High viscosity  high mechanical energy  overheating of elastomer   Plug flow kneader reactor  Discharge target of ppm solvent  Process elastomer as crumbles (or pasty phase)

10/11/2011 – p. 9 Two Step Process for Direct Devolatilization  Installed at Fraunhofer Gesellschaft, Schkopau, Germany  Part of larger semi works plant for polymer synthesis, production, and testing

10/11/2011 – p. 10 Main Evaporation Experimental  100 liter single shaft kneader reactor  Residence time of 15 minutes  Shaft speed of RPM Elastomer Solution 400 kg/hr 10% BR 100°C Pasty Elastomer Hot Oil 80°C 300 mbar Hot Oil

10/11/2011 – p. 11 Finishing Experimental  200 liter twin shaft kneader reactor  Residence time of 30 minutes  Shaft speed of 60 RPM Pasty Elastomer Crumbly Elastomer 60 mbar 40 kg/hr Hot Oil 80°C Hot Oil

10/11/2011 – p. 12 Main Evaporation Temperature Profile Thermal Input Mechanical Input Thermal Output Energy Required Feed

10/11/2011 – p. 13 Main Evaporation Energy Balance Solvent Evaporation 35 kW 27 kW (77%) mechanical energy Elastomer Solution 300 mbar ~65 °C (estimated) 400 kg/hr 10% BR 100°C Pasty Elastomer 44 kg/hr 90% BR 97°C 8 kW (23%) thermal energy

10/11/2011 – p. 14 Finishing Energy Balance 60 mbar Devolatilization 0.5 kW 4.6 kW mechanical energy Pasty Elastomer 40 kg/hr 1000 ppm Solvent 87 °C 44 kg/hr 90% BR 97°C Crumbly Elastomer 4.1 kW thermal energy

10/11/2011 – p. 15 Finishing Improved Mass Transfer Process

10/11/2011 – p. 16 Finishing Improved Mass Transfer Process Finisher sizeCapacityfinal VOCtotal volatiles 7 liter2.5 kg/hr< 10 ppm5000 ppm 30 liter30 kg/hr< 50 ppm5000 ppm 100 liter50 kg/hr< 50 ppm5000 ppm 200 liter50 kg/hr< 15 ppm5000 ppm  BR in hexane  Atmospheric pressure

10/11/2011 – p. 17 Comparison to Conventional Process  Energy  Environment  Flexibility  Operation  Footprint  Quality

10/11/2011 – p. 18 Conclusion  Conventional process for temperature sensitive elastomers Mature and proven technology Several key disadvantages  Two step process for direct devolatilization Kneader reactor technology Removes water from process Demonstrated process on semi works scale