Using Additional Layers in Co-extruded HDPE Moisture Barrier Films to Enhance Properties

摘要

High-density polyethylene (HDPE) is commonly used to provide moisture barrier performance in flexible packaging such as dry food packaging such as cereal liners. These films are often made on 3-layer blown film lines whereone layer consists of a sealant formulation and the remaining two layers are comprised of HDPE. In the past, down-gauging of these film structures was limited by the moisture barrier performance of the HDPE materials available. With the advent of "ultra-high" barrier HDPE materials, barrier performance is no longer the limiting factor in the design of these film structures'1'. Film processors find film toughness is now the limiting factor preventing further gauge reductions. Toughness properties can be improved by incorporation of high toughness material such as single site catalyzed LLDPE but the ability to use these types of materials is very limited in a 3-layer structure.This report details the technological advantages of systematically designing (engineering) a 5 or 7 layer structure with the appropriate building blocks/materials. The incorporation of high toughness materials allowed significant down-gauging without decreasing barrier performance.