| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film useful as a magnetic recording medium having a magnetic layer of vapor deposition type in particular, in which the surface characteristics of the polyester film consisting of both a polyester having excellent dimensional stability and a polyimide are improved, and dense projections are formed on the surface and thereby electromagnetic conversion characteristics, stability of a vapor deposition process and enhancement of quality are contrived. SOLUTION: The polyester film for the magnetic recording medium has a basic layer part (layer A) comprising a polyester and a polyimide as an essential component. The whole thickness constituted of a film layer of at least two or more layers is 3-8μm. In the laminated polyester film, projections having 5-25 nm height of a projection exist in a rate of 5-7 million pieces/mm2 on the surface ((f) face) of one hand. Surface roughness Raf on the (f) face side is 0.1-5 nm and the surface roughness Rab of the surface ((b) face) on the opposite side is 5-20 nm. Numbers H1, H2 of rough and large projections on the surface of the film on the (f) face side are in a specified range.
|
