| 摘要 |
PURPOSE:To perform higher density recording by utilizing high picture quality of a metal thin film magnetic recording medium and high strength, high heat resistant characteristics of fundamental characteristics of polyethylene-2,6- naphthalate. CONSTITUTION:A biaxially oriented composite film has a layer A made of polyethylene-2,6-naphthalate containing germanium compound and magnesium compound, and a layer B made of polyethylene-2,6-naphthalate containing inactive solid fine particles and laminated on the layer A. The layer A is covered with a coating film in which a discontinuous film or fine particles having a mean particle size of 3nm or more or both exist in such a manner that its surface roughness is 5nm or less. The layer B is formed of polyethylene-2,6- naphthalate containing 0.001-1wt.% of particles having mean particle size of 0.1-0.5mum and a biaxially oriented composite polyethylene naphthalate film for a metal thin film magnetic recording medium has a surface having surface roughness of 25nm or less. |
