| 摘要 |
PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film having uniform projection height, reduced in undulation, excellent in abrasion resistance and having high strength, excellent quality and high productivity, and a method for producing the same. SOLUTION: A biaxially oriented polyester film is characterized by that the ratio Rt/Ra of the max. height Rt of the surface of the film measured according to JIS B-0601 (3.1.1) and the center line surface roughness Ra measured according to JIS B-0601 (4.1.1) is 15 or less and the undulation index defined in the body is 10 or less. This biaxially oriented polyester film is produced by crystallizing at least the single surface of the surface layer of an unstretched film cooled and solidified after melt extrusion to form projections on the surface of the film and biaxially orienting this film and the crystallization of the surface layer of the unstretched film is performed by heating the part other than the edge parts of 20 mm or less from both end parts of the film in a non-contact state. |
