| 摘要 |
PURPOSE: To obtain a polyester film which does not contain voids, has projections difficult to break, and has a greatly improved resistance to powder generation by shaving of the film surface, of which the projections have minute sizes, a high density, and uniform heights, and of which both the film roll appearance and the output characteristics, formerly thought to be incompatible with each other, are greatly improved. CONSTITUTION: This polyester film mainly comprises polyester A and satisfies the conditions that the projections on at least one side of the film are caused mainly by crystals of polyester A, that the ratio of surface roughness parameters Rz/Ra is from 4 to less than 12, that the dispersion of Ra [=100×(the max. value of Ra - the min. value of Ra)/mean value] is 30% or lower, and that the particle density at the depth of 5 times the mean projection height is 10,000/mm<2> or lower at near the surface of the section in the direction of film thickness. |
