High-strength, biaxially oriented polypropylene film

摘要

Biaxially oriented polypropylene (boPP) film contg. a resin (I) ha a n-heptane-insol. component with an isotacticity index of at least 85-94% (by <13>C-NMR spectroscopy) and is stretched so that the product of its tensile strengths in the longitudinal and transverse directions is greater than 50,000 (N/mm<2>). Also claimed is the prodn. of this film by compressing and melting the polymer(s) in an extruder, extruding the melt through a sheet die, drawing off and recompacting over take-off roller(s), and orienting the film in both directions so that the prod. of the longitudinal and transverse stretch ratios (LSRxTSR) is at least 60.