PURPOSE: To obtain a biaxially orientated polyester film for magnetic recording media, excellent in electromagnetic transduction characteristics and light screening property, by dispersing specified inert particles and a light absorber in a polyester.
CONSTITUTION: 0.03W3wt% inert particles (B) of an average particle diameter of 0.01W2.0μm (e.g., TiO2) and a light absorber (C) which is an organic compound which shows the maximum light absorption at a wavelength between 700 and 1,100nm [e.g., bis(cis-1,2-diphenylethylene-1,2-dithiolato)palladium] are dispersed in a polyester (A) obtained by polycondensation of an aromatic dicarboxylic acid component with a glycol component (e.g., polyethylene terephthalate), melt-extruded, biaxially orientated and heat-set to obtain a biaxially orientated polyester film having a surface roughness ≤0.025μm and a transmittance (at a wavelength of 900nm)≤50%.
TOMITA HIROSHI
KATO HIDEO
