BIAXIALLY ORIENTED POLYESTER FILM

摘要

PROBLEM TO BE SOLVED: To provide a laminated polyester film capable of unsealing straightway without splashing the packed contents and excellent in preventing powder from sticking to the film. SOLUTION: This polyester film has at least one layer having sea/island structure. The sea/island structure satisfies both formulas of 50<=X/Y and 5<=N<=200 simultaneously [wherein, X is an average value of the length of film in a longitudinal direction at island portion (μm); Y is an average value of the length of film in a width direction at island portion (μm); and N is the number of island portions located at the section in film width direction (piece/μm2)], and the film-surface resistivity is to be below 1×1015Ω/square.