04.11.06
A polyester film has received a patent. The film surface portion contains no protrusion with 10 nm or more in height and constitutes at least 5% of the whole film surface. The number of protrusions with not less than 3 nm and less than 5 nm in protrusion height in the film surface portion is not less than 1x106/mm2 and less than 1x109/mm2.