POLYESTER FILM FOR MEGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING TAPE

摘要

PURPOSE: A polyester film for a magnetic recording medium is provided to allow production of digital videotapes with good electromagnetic conversion property and to reduce dropouts from any portion of the entire length of the film rolled. CONSTITUTION: The polyester film for magnetic recording medium formed by layering a polyester layer A and a polyester layer B is characterized in that the surface of the layer A side has 2-4 nm centerline average surface roughness (SRa value) and 10-40 nm ten-point average surface roughness (SRz value) and the layer B contains fine particlesαhaving >= 50 nm and <250 nm average particle size and fine particlesβhaving >= 250 nm and <500 nm average particle size and fine particlesαcontent and fine particlesβcontent in the layer B are 0.1-1.0 wt.% and 0.01-0.1 wt.%, respectively. A magnetic recording tape is formed by providing a ferromagnetic metal thin film on the surface of the layer A side of the polyester film.