EXTRUSION: Another Way to Extrude PET Without Drying

A planetary-roller section allows efficient degassing.

Add another to the list of machine builders offering PET sheet extrusion lines that require no predrying. Austria’s Battenfeld-Cincinnati (U.S. office in McPherson, Kan.) recently commissioned a three-layer, no-dry PET sheet line for packaging giant Paccor International GmbH in Germany. The coextrusion line includes an inline lamination station and was installed at Paccor’s plant in Skierniewice, Poland. Since last August, Paccor has been producing sheet from 200 microns to 1.2 mm thick at rates exceeding 2200 lb/hr.

The extruder on this line has a standard single screw equipped with a planetary-roller section in the degassing area. According to the machine builder, this configuration causes the melt to be spread out in very thin layers, generating an extremely large surface area for degassing through a single vent port, thus permitting use of undried PET bottle scrap.

The planetary section is followed by asecond, short single screw to build pressure(see photo far right). For virgin PET, Battenfeld-Cincinnati recommends preconditioning the material to 1000 ppm moisture in lieu of drying.

Three extruder sizes are available: 90, 120, and 150 mm. The line reportedly can also be used to process PLA, PP, or PS without changing the screw.

Other suppliers of no-dry systems include Coperion, Ramsey, N.J.; Entek Extruders, Lebanon, Ore.; Gneuss Inc., Charlotte, N.C.; Leistritz Extrusion, Somerville, N.J.; Processing Technologies International (PTi), Aurora, Ill., through its relationship with Italian twin-screw builder Luigi Bandera; and Welex, York, Pa., via its arrangement with Austria’s conical-twin builder MAS GmbH.