POLYESTER FILM FOR MAGNETIC RECORDING MEDIUM AND MAGNETIC RECORDING TAPE

摘要

PROBLEM TO BE SOLVED: To provide a polyester base film suitable for manufacturing a digital video tape with excellent electromagnetic conversion characteristics and little DO(drop out) even when the vapor deposition rate is increased. SOLUTION: The polyester film is obtained by laminating a layer A which forms one side surface (a) with a layer B which forms the other side surface (b). The SRa value and SRz value of the surface (a) are 2 to 5 nm and 10 to 40 nm, respectively. The layer B contains fine particlesαto form surface projections on the surface (b), and the average particle size of the fine particlesαis >=250 nm and <500 nm. Surface projections having 150 to 500 nm height are formed on the surface (b) by 5×103 to 1×105 particles/mm2 density. No smoothening coating layer is formed by coating in the outside of the surface (b). The polyester film for a magnetic recording medium is used by forming a ferromagnetic metal thin film layer in the outside of the surface (a).