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A DEVICE FOR DEVOLATILIZATION OF POLYMER MELTS

IP.com Disclosure Number: IPCOM000128591D
Publication Date: 2005-Sep-16
Document File: 1 page(s) / 27K

Publishing Venue

The IP.com Prior Art Database

Abstract

The present invention concerns a devolatilization device which relies on increased free surface area for volatiles exposure with possibility of using all techniques available to an extruder system such a vacuum and application of stripping agents. The device uses multiple co-rotating or counter-rotating intermeshing, non-intermeshing or partially intermeshing screws in an enclosure with vacuum pulling capability. The screws are (size and number) designed in such a way to operate in a partially filled mode and will use molten polymer supplied by an upstream system (single or twin screw extruder, continuous mixer, etc.). The polymer stream is first spread through a melt manifold in the form of molten strands to maximize free surface area. The strands are then collected by the screws and conveyed downstream for additional surface renewal. For improved devolatilization, a control device can be added to control polymer passage.

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A Device for Devolatilization of Polymer Melts

Existing technology has been limited in its ability to devolatilize polymer melts.  

The present invention concerns a devolatilization device which relies on increased free surface area for volatiles exposure with possibility of using all techniques available to an extruder system such a vacuum and application of stripping agents.  The device uses multiple co-rotating or counter-rotating intermeshing, non-intermeshing or partially intermeshing screws in an enclosure with vacuum pulling capability.  The screws are (size and number) designed in such a way to operate in a partially filled mode and will use molten polymer supplied by an upstream system (single or twin screw extruder, continuous mixer, etc.).  The polymer stream is first spread through a melt manifold in the form of molten strands to maximize free surface area.  The strands are then collected by the screws and conveyed downstream for additional surface renewal.  For improved devolatilization, a control device can be added to control polymer passage.

This control device will adjust the size of a melt pool at its leading edge.  Pool recirculation will generate additional surface renewal and volatiles exposure.  Screw profiles can be designed for injection and mixing of a stripping agent at a high pressure point (a screw mixing section beneath the control device for example).   Devolatilization is usually improved with higher screw speeds (surface renewal) and...