| abstract |
(57) [Summary] [PROBLEMS] To provide a biaxially oriented polyester film which has a flat surface, few coarse projections, excellent running properties and winding properties, and which can be economically produced. [Structure] (1) The particle size distribution ratio (γ) is 1.3 to 3.5, (2) the average particle size is 0.1 to 2 μm, and (3) Polyester containing 0.01 to 5% by weight of crosslinked polymer particles characterized by having a non-circularity of 3.4 or more, and (4) a standard deviation of the non-circularity of at least 0.16. A biaxially oriented polyester film formed from |