BIAXIALLY STRETCHED POLYPROPYLENE WITH ROUGHENED SURFACE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To prepare an OPP film with a controlled surface roughness and a process for producing the same. SOLUTION: The surface roughness of at least one side of a biaxially stretched polypropylene film prepd. from a polypropylene resin is adjusted so that: (a) the 10-points mean roughness (Rz) is 1.0μm or higher; (b) the center line roughness (Ra) is 0.15-0.3μm; and (c) the max. height (Rmax) is 1.3μm or higher. In order to achieve such a surface roughness, at least one side of a sheet prepd. from a polypropylene resin having a heptane index of at least 96.5% is adjusted so that the following requirements are satisfied: (a) the amt. ofβ-crystals (K value) of PP is 15% or higher; and (b) the number ofβ-crystals of PP per unit area is 10,000 or higher.