Processing Technologies Inc. of St. Charles, Ill., has built a coextrusion sheet line that can run up to seven layers. The line is designed to run with an in-line thermoforming machine.
PTI supplied the line to a large Midwest packaging company, which it did not identify. The line produces high-barrier polypropylene/ethylene vinyl alcohol-based sheet for containers.
The line includes five PTI Trident Series extruders — a main extruder with a screw diameter of 6 inches, one 3.5-inch, two 2.5-inch and one 2-inch extruder.
Coextrusion of up to seven layers is done with a Cloeren Inc. multimanifold die combined with a coextrusion feedblock. Cloeren is based in Orange, Texas.
The 6-inch main extruder and one satellite extruder are equipped with melt pumps for thickness uniformity, and static mixers for better thermal homogenization.
A control system monitors all temperature zones and drives. It also does die-bolt control for automatic control of sheet thickness.
The line comes with PTI´s J-Stack, a three-roll cooling and polishing stack.
A primary nip is installed at a 40-degree angle to the centerlines of the extruder, allowing for a close approach and a reduced air gap. That also helps in processing materials with a low melt strength, which tend to sag when entering the nip on a horizontal layout.
The other two rolls are positioned vertically.
PTI´s Auto-Gap servo-hydraulic roll positioning system automatically sets and controls the nip roll gap.
Tel. (630) 443-3000, fax (630) 443-0333, e-mail [email protected]