Película de polipropileno biaxialmente orientada processo para sua produção e suas aplicações

摘要

Biaxially oriented polypropylene (BOPP) film with at least one base layer (A) contg. polypropylene (PP) is claimed, in which (a) the isotactic block length of the PP between two structural defects is more than 40 (statistical average), (b) the n-heptane- insol. component of the PP has an isotacticity (by <13>C-NMR spectrometry) of at least 95%, (c) the PP has a mol. wt. ratio Mw/Mn of less than 4 and contains less than 1% n-heptane-soluble component, and (d) the film has a tear strength of more than 15 N/(mm film thickness) in both the machine (longitudinal) and transverse directions. Also claimed is a process for the prodn. of this BOPP film, which involves orienting the film by stretching in the machine direction by a factor of (3:1)-(9:1) and in the transverse direction by a factor of (4:1)-(12:1).