IMPROVED COMPOSITION FOR UNIAXIALLY HEAT-SHRINKABLE BIAXIALLY ORIENTED POLYPROPYLENE FILM

摘要

A uniaxially heat-shrinkable, biaxially oriented, multilayer film having a polypropylene-containing core layer comprising at least 70 wt.% of said multilayer film and optionally, at least one polyolefin-containing skin layer adjacent said core layer, is prepared by biaxially orienting a coextrudate and thereafter orienting said coextrudate by stretching 10 to 40 % in the machine direction. The core layer contains isotactic polypropylene and a sufficient amount of syndiotactic polypropylene to inhibit uniaxial heat shrinkage at temperatures below 50 DEG C. The skin layer can be selected from the group consisting of polypropylene, ethylene-propylene copolymer, polyethylene, and ethylene-propylene-butylene terpolymer.