| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a polyester film to be used as a base suitable for a data recording tape, which is excellent in productivity and electromagnetic conversion characteristics of a base film with fewer errors and particularly, achieves high-density magnetic recording, as a polyester film for a magnetic recording tape with a large capacity allowing high-density recording. <P>SOLUTION: The polyester film for a magnetic recording tape is a laminate film including a polyester layer A and a polyester layer B, a coating layer I on a surface A of the polyester layer A in the opposite side to the polyester layer B, and a surface B as the surface of the polyester layer B in the opposite side to the polyester layer A, and satisfies the following conditions (a) to (d). (a) The coating layer I provided on the surface A contains inert particles I having an average particle diameter of 5 to 60 nm; the average surface roughness on the coating layer I is 2 to 6 nm; and dents having a depth of 7 nm or more are present by 5,000/mm<SP POS="POST">2</SP>or less on the coating layer I. (b) The polyester layer A is a polyester layer containing substantially no inert particles and having a layer thickness of 3.0 μm or more. (c) The polyester layer B is a polyester layer containing inert particles B having an average particle diameter of 0.1 to 1.0 μm. (d) The surface B shows an average surface roughness Ra of 8 to 20 nm and a ten-point average roughness Rz of 300 nm or less. <P>COPYRIGHT: (C)2013,JPO&INPIT |
