| 摘要 |
PURPOSE:To obtain the title film excellent in electromagnetic transduction characteristic, surface flatness and running performance and low in transmittance, by dispersing carbon black and specified inert solid fine particles in a polyester and molding the mixture. CONSTITUTION:0.5-2.5wt% carbon black (B) of an average particle diameter of 0.02-1mum, 0.05-2.0wt% (equivalent to a weight ratio to component B of 0.05-0.8) inert solid particles (C) of an average particle diameter of 0.1-0.5mum, and an optical refractive index >=1.8, which are preferably TiO2, black iron oxide, ZnO or lithopone and, optionally, 0.03-1wt% inert particles, as a lubricant, (e.g., SiO2) of an average particle diameter of 0.1-1.2mum are dispersed in a polyester (A) comprising an acid component based on an aromatic dicarboxylic acid and a glycol component based on an aliphatic glycol, and the mixture is formed into a membrane and biaxially orientated to obtain the title film of a transmittance at a wavelength of 900nm<=30% and a surface roughness of 0.007-0.024mum. |
