| 摘要 |
PURPOSE:To obtain a film excellent in electromagnetic transduction properties, travelling properties and abrasion resistance, having a low light transmittance and being useful for a magnetic recording medium by using a polyester in which a specified carbon black and specified inert spherical particles are dispersed so as to give thereto specified physical properties. CONSTITUTION:This film is comprised of a polyester (e.g. polyethylene terephthalate) in which 0.1-5wt.% carbon black of a mean particle diameter of 0.01-0.6mum and 0.01-3wt.% inert spherical particles (e.g. silica particles, silicone particles or crosslinked PS particles) of a mean particle diameter of 0.1-1.2mum and an aspect ratio (major diameter/minor diameter ratio) of 1.0-1.4 are dispersed. It has a thickness of 4-15mum, a transmittance <=70% at a wavelength of 900nm and a Young's modulus >=630kg/mm<2> in the crosswise direction and a surface roughness <=0.025mum. |
