Go Beyond Adhesion: the Dual Functionality of Tie Layers

Go Beyond Adhesion: the Dual Functionality of Tie Layers

Brian Walther
Material Advances and Their Benefits

Dual functionality tie-layers, combining adhesion and an additional function in the same layer, can enable a targeted improvement in multilayer barrier films. A tough tie-layer and a barrier tie-layer are examples of innovations based on this concept. A tough tie-layer has been developed with the most recent LLDPE technology. Beyond adhesion, the tie resin imparts enhanced abuse resistance to the film. A barrier tie-layer, on the other hand, has been developed to enhance the barrier properties of the film. It is well known that the gas barrier properties of EVOH deteriorate when the film is exposed to high moisture or relative humidity. One way to get around this problem is either to position HDPE or Nylon around EVOH to prevent moisture ingression or use an extra amount of EVOH to compensate for the barrier loss. The barrier tie layer solves the problem without resorting to additional materials. The results have shown significantly improved oxygen barrier for EVOH under conditions of high relative humidity as well as excellent adhesion to EVOH. The dual functionality of tie-layers brings additional value to brand-owners in terms of extended shelf life and extra product protection without changing the film structures.