| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems such as insufficient contact between the recording medium and a magnetic head due to the poor stiffness of the film, the bend of the tape during its running and deteriorated process passing property during the manufacturer of the magnetic recording medium; to provide a polyester film for a magnetic recording medium by which the magnetic recording medium excellent in output, drop-out characteristics and error rate characteristics is obtained; and to provide a magnetic tape using the polyester film. SOLUTION: The polyester film for a magnetic recording medium has the following properties for its one surface simultaneously: (1) The number of fine projections, whose average height is between 3 nm and 50 nm, is in a range of 3×10<SP>6</SP>pieces/mm<SP>2</SP>to 60×10<SP>6</SP>pieces/mm<SP>2</SP>, (2) Surface roughness (ARa) determined by an atomic force microscope (AFM) is in a range of 0.4 nm to 2.5 nm, and (3) Surface roughness (WRa) determined by a noncontact three- dimensional surface roughness guage is in a range of 0.3 nm to 3.0 nm. In addition, Young's modulus of the magnetic film is at least 5,000 MPa in the longitudinal direction and at least 10,000 MPa in the lateral direction. COPYRIGHT: (C)2004,JPO |
