| 摘要 |
PROBLEM TO BE SOLVED: To provide a base polyester film for large-capacity magnetic recording tape adapted to high density recording, having excellent electromagnetic conversion characteristics, improved durability while reducing the number of dropouts in repeated use of the magnetic tape, and suitable for DVCAM or HDV that requires high image quality and high reliability.SOLUTION: In the polyester film for magnetic recording tape, a coating layer containing a water-soluble polyester resin and an inert particle with an observation average particle diameter of 25-60 nm is formed on a polyester layer, and a magnetic layer is formed on the side where the coating layer is formed. The coating layer has a solid content mass of 7-25 mg/mand contains the water-soluble polyester resin of 70-85 mass% to a gross mass of the coating layer. The number density of projections resulting from the inert particles on the surface where the coating layer is formed (hereinafter referred to as surface I) is 5,000-500,000 pieces/mm, an average plane roughness Ra of the surface I is 2.5-5.5 nm, and ten-point average roughness Rz (nm) and Ra of the surface I satisfy 25>Rz/Ra>13. |
