Heterogeneous membranes from highly filled thermoplastic orientable polymers

摘要

A film having a porous core layer and nonporous outer layers is disclosed. It is suitable for controlled atmosphere packaging end uses. The film is made from a composition of certain polymers, particularly ethylene polymers, a particulate filler which has little affinity for the polymer, and optionally an organic compound which decreases the tendency for affinity of the particulate for the polymer. The film is produced by extruding the composition through a die gap of at least 250 mu m, and subsequently stretching the film after cooling to a temperature below the melting temperature of the polymer.