| 摘要 |
PURPOSE:To obtain the title film excellent in lubricity, chipping resistance, adaptable for high-speed processing and suitable as a base film for videotapes, by forming a composition comprising a polyester and inert inorganic particles into a film and biaxially orienting this film. CONSTITUTION:0.3-3.0wt.% slurried inert inorganic particles (e.g., TiO2) of an average particle diameter of 0.05-0.6mu are dispersed in a diol component (e.g., ethylene glycol) of a polyester and an acid component [e.g., terephthalic acid (dimethyl ester)] is added to this diol component. The mixture is transesterified and polycondensed to obtain a composition comprising a polyester and the inert inorganic particles. An unoriented film formed by extruding this composition at 270-330 deg.C with a melt extruder is biaxially oriented at a draft ratio of 3.0-5.0 and a speed of orientation of 1X10<3>-7X10<4>%/min and heat- treated at 180-250 deg.C for 0.5-60sec without elongation to obtain the title film satisfying the relationships of formulas I-III [wherein D is the average particle diameter (mu) of the inert inorganic particles; Ra is the average surface roughness (mu) along the direction of the film width; and H is the average height (mu) of surface protrusions] and having a surface orientation index of 0.935-0.970, a density index of 0.02-0.05, etc. |
