No-Dry PET Sheet Can Be Foamed Too

Gneuss Extrusion Technology is showing a complete Gneuss Processing Unit (GPU) comprised of a Multi Rotation System (MRS) 130 extruder, an RSFgenius 150 fully automatic melt filter, and the VIS online viscometer. The line is made for processing undried, uncrystallized PET at rates up to 2000 lb/hr.

The MRS extruder permits PET to be processed without pre-drying by using a simple water- ring vacuum system. The machine has a unique and patented processing section that’s based on a conventional single-screw extruder; it’s a drum containing eight satellite single screws, driven by a ring gear-and-pinion transmission. The “barrels” cut into the drum are approximately 30% open and provide optimum exposure of the melt.

Thanks to this design, devolatilizing performance is said to be 50 times greater than a conventional single-screw extruder—at a vacuum of only 25 to 40 mbar. By avoiding the need for a deep vacuum system and pre-drying, the MRS is billed as an economically efficient alternative to conventional technologies. 

The system is most commonly used in PET sheet processing. And a new foam module now permits processors to quickly switch from rigid to physically foamed PET. Foam sheet with a weight reduction of 50% can be extruded (depending on the process) with a consistent foam structure and mechanical properties from up to 100% post-consumer material, says Gneuss.