BIAXIALLY ORIENTED POLYPROPYLENE FILM HAVING IMPROVED MECHANICAL AND BARRIER PROPERTY

摘要

PROBLEM TO BE SOLVED: To enhance steam and oxygen barrier properties and mechanical physical properties by adding propylene produced using a metallocene catalyst and specified in average isotactic block length, the content of n-heptane insolubles and solubles and wt. average mol.wt./number average mol.wt. ratio to the base layer of a film. SOLUTION: In a biaxially stretched polypropylene film having at least one base layer containing polyolefin, polypropylene in the base layer is produced by using a metallocene catalyst and characterized by that the average isotactic block length of polypropylene molecules between two structural carbon chain flaws exceeds 40 as a statistical average, n-heptane insolubles of polypropylene have at least a 95% carbon chain isotactlc index in a<13> C-NMR spectral method, a ratio of a number average mol.wt. Mn to a wt. average mol.wt. Mw is below 4 and n-heptane solubles are below 1%.