By now the reader is probably wondering if it is possible to produce a Nylon-PVdC barrier film for draw forming applications? The challenge of coextruding Nylon and PVdC in the same structure is that the high temperature required to process the Nylon will degrade the heat sensitive PVdC. Depending on the type, Nylon is processed between 150ºF to 180ºF (80ºC to 100ºC) hotter than PVdC. In a typical coextrusion die, the extra heat applied to the Nylon layer will sink into the rest of the die, including the PVdC layer, and cause it to degrade. Macro was the first company to solve this problem approximately two years ago in a lab line with a 5” (127 mm) 6-layer die. A 5-layer TaperPack™ die (suitable for smaller sizes) with a 6th layer for Nylon was used. The Nylon mandrel was thermally isolated by an air gap from the rest of die. This method of thermal isolation is simple and elegant, without the need of complicated ancillary systems. The Nylon layer meets the other layers only ½” (13 mm) before exiting the die lips thus preventing the PVdC degradation. A typical structure produced with this setup would be Nylon/tie/EVA/PVdC/ EVA/LLDPE.
Obviously that it is one thing to be successful producing a Nylon-PVdC coextrusion in a lab line with a 5” (127 mm) die and another to repeat the same success commercially with an 14” (356 mm) or larger die. It is in commercial applications where the unique features and advantages of the AMT MacroPack™ die design make it the ideal solution for the production of Nylon-PVdC barrier films. Other draw forming structures that are possible with the AMT MacroPack™ die include Polystyrene-PVdC barrier films.
