Seven Layer Co-Extrusion Line
Schematic of Seven Layer Co-Extrusion Line
Welex Coextrusion Line
In 1994, the Polymer Processing Institute assumed the responsibility of the start-up of the seven layer coextrusion line at the New Jersey Institute of Technology (NJIT) and successfully completed the task in three months. This seven layer coextrusion pilot line, which PPI is currently managing, consists of two 2.5" single screw extruders and two 1.25" single screw extruders. The line is complete with one master drier and two satellite driers which are mounted on the two 2.5" extruders. Vacuum loaders, air tight transfer lines and automatic controllers are used for drying moisture sensitive materials in the main drier and feeding these materials to the satellite driers. Each of the two 2.5" extruders is equipped with two auxiliary side feeders for metering-in small but precise amounts of additives, screen changer for filtering-out the un-melted material and a Maag gear pump for metering melt to the die at constant pressure. Under normal operations, the extruder is slaved to the gear pump controller. All four extruders and side feeders are connected to a master control potentiometer which can speed up or speed down the line without changing the relative proportions of the individual components.
The line is equipped with a manifold to produce up to seven layers of coextruded sheet when all four extruders are used. The configuration could easily be changed so that one can also extrude a sheet with coextruded layer on one of the sides. A 34" wide adjustable sheet die is currently being used to extrude sheet of thickness between 30 mil and 120 mil. Three stack polishing rollers, on-line thickness gauge and edge trim winders are part of this line. A 10" wide sheet die with adjustable lip is also used in this line for special applications.
The line has been successfully used for developing a process for the production of foamed core polyolefin and polyester sheets of thickness up to 120 mil. PET, HDPE, LDPE, PS, ABS, Cellulose Acetate, PMMA, EVA and various other polymers are also extruded to produce mono-layer or multi-layer sheets for thermoforming
For more information please contact
Dr. Linji Zhu