32 / 46
Extrusion International 2/2016
32
Flow control
and versatility of coextrusion
A coextrusion die system from Nordson Corporation
has enabled an extrusion processor specializing in
PET-based semi-rigid packaging sheet to maintain
layer uniformity well within tolerances while
avoiding product defects arising from asymmetrical
layer structures.
E
vertis de México S.A. de C.V., a manufacturer of thermo-
formable sheet for food packaging such as poultry, cheese,
and processed meat, as well as non-food applications, recently
installed a Nordson EDI coextrusion die system for producing a
range of structures. These include standard multi-layer, medium-
barrier, and high-barrier sheet with thicknesses from 180 to
1,016 µ (0.180 to 1.016 mm). The barrier sheet structures are
often asymmetrical, in that the materials or layer thicknesses
above the central layer differ from those below it. The precision
flow control of the Nordson EDI system has made it possible to
maintain tight layer tolerances in such structures while prevent-
ing “wave,” “zig-zag” and other defects caused by instabilities
at the interface between layers.
“At Evertis we strive to improve our production methods and