| 摘要 |
PURPOSE:To obtain the title polyester film improved in chipping resistance and running performance, by incorporating an oxide of a sixth period element of a specified means particle diameter and specifying the standard deviation of the heights of the surface protrusions in a specified range. CONSTITUTION:This biaxially oriented polyester film contains an oxide of an element of the sixth period of the periodic table, wherein the mean particle diameter of said oxide in the film is 0.1-2.5, desirably, 0.15-2.0, more desirably, 0.15-1.5mum, and the standard deviation of the distribution of the surface protrusions on at least either surface is in the range of 30-500, desirably, 40-300, more desirably, 50-250nm. As said oxide, an oxide of a lanthanoil element is desirable, and cerium oxide is particularly desirable. It is particularly desirable that the content of said oxide is 0.1-1.5wt.%, the coefficient of promoting crystallization of particles is 5-30 deg.C, and the density of said oxide is particularly desirably 4.0-8.5g/cm<3>. |
