BIAXIALLY COLD-STRETCHED VINYLIDENE FLUORIDE POLYMER FILM AND ITS PREPARATION

摘要

PURPOSE:To prepare a biaxially cold-stretched vinylidene fluoride polymer film excellent in the mechanical strengths at a low cost by biaxially cold- stretching a specific vinylidene fluoride polymer by the inflation process. CONSTITUTION:A vinylidene fluoride polymer having an inherent viscosity of 0.8-1.6dl/g and a ratio of the wt.-average mol.wt. to the number-average mol.wt. of 10-20, or a polymer mixture comprising at least 30wt.% above- mentioned vinylidene fluoride polymer and 70wt.% or lower vinylidene fluoride polymer having a ratio of the wt.-average mol.wt. to the number-average mol.wt. of 10 or lower is biaxially cold-stretched pref. in a stretching ratio of at lest 1.5 in both the longitudinal and transverse directions by the inflation process.