Effect of Back‐layer on seal performance of multilayer polyethylene‐based sealant films

Abstract

This work studies effects of back‐layer materials, thickness of sealant layer, and sealing condition on seal performance of multilayer polyethylene‐based films. Multilayer films with back‐layers of high‐density polyethylene (HDPE), or low‐density polyethylene (LDPE), or linear low‐density polyethylene (LLDPE) were produced with different thicknesses of the metallocene layer. It was found that increasing the thickness of the metallocene layer improved hot tack properties. In addition, films with back‐layers of LLDPE or LDPE showed higher hot tack strength compared to those with HDPE back‐layer. Increasing sealing temperature reduced significantly the hot tack strength and its dependency on metallocene layer thickness. It was found that increasing delay time after sealing, before peeling test, increased hot tack strength, but the rate of hot tack evolution and the type of peeling behavior were considerably affected by the type of back‐layer material. The effect of dwell time was also examined, and it was observed that increasing dwell time in the studied range did not affect the hot tack evolution. The mechanisms involved in the development of hot tack evolution were discussed, and it was shown that the back‐layer effects can be explained by bulk viscoelastic energy dissipation theory.