BIAXIALLY ORIENTED POLYESTER FILM

摘要

PURPOSE:To obtain the subject film useful for a magnetic tape, etc., having excellent transparency and smoothness containing a specific amount of colloidal silica containing a specific amount of alkali-metallic compound. CONSTITUTION:The aimed film contains 0.01-2wt.% colloidal silica (averaged particle diameter is preferably 0.15-1mum) containing 0.004-0.02mol, preferably 0.006-0.016mol alkali-metallic compound calculated as an alkali-metallic oxide (M2O) per 100g colloidal silica.