Modification of Polypropylene Resins with Nucleating Agents to Enhance Mechanical and Barrier Properties of Films

Abstract

This invention relates to packaging applications. It generally relates to polyethylene or ethylene/α-olefin copolymer based co-extruded, multi-layer films or sheets—rigid or flexible—for thermoforming into shaped containers such as packaging containers. Inter alia, the films have improved barrier properties, toughness, and snapability. Particularly, the films of the present invention comprise one or more stacks of polypropylene layers, wherein at least one stack comprises nucleating agents. In one embodiment, the polypropylene layers in the stack are provided such that any two adjacent layers have different microstructures that provide a interface or interphase between the two layers with likely different microstructures and/or crystallinity. The overall polypropylene stack structure assists in disrupting the transport of oxygen, thereby providing a laminate or structure, for example a rigid film or sheet, with enhanced oxygen-barrier properties. The invention also relates a process for preparing shaped articles such as containers from such films, and to such shaped articles-rigid or flexible-both filled and unfilled.

Dependencies are inferred from the claim text.