High Moisture Environments and Extrusion Coated / Laminated Products
When extrusion coating or extrusion laminating with a polyethylene extrudate, a primer is typically used to promote adhesion. The most common primer, polyethyleneimine (PEI), has been successfully used for a wide variety of EtO and radiation sterilized medical device applications for over thirty years. This primer is a very economical way to provide virtually indestructible bonds for most applications
However, the extrusion-coating or extrusion-laminating bond can be compromised under certain circumstances. When the primer is exposed to water or very high humidity environments, the primer bond can be attacked and break down.
Materials with PEI primers should be carefully tested before using them for liquid-holding applications. While they are ideal for most other applications, there have been a few isolated cases where delamination has occurred during the qualification process when the product has been exposed to multiple EtO sterilization cycles and/or extreme environmental challenges (e.g. 50°C and 80% RH). When designing qualification testing, care should be taken to ensure the exposure conditions are consistent with what the package is likely to experience. We are aware of no cases where medical device manufactures have had field failures after approving extrusion-coated or extrusion-laminated structures using PEI primers.
For those demanding applications requiring water or very high-moisture resistance, alternate extrusion-coated and extrusion-laminated structures are available. In these structures, the PEI primer has been replaced with either a water-tolerant primer or a tie layer. Alternatively, an adhesive lamination may be considered. Your account representative can help guide your choice.