PURPOSE: To improve quality by using a polyester polymer layer contg. spherical inert particles as one outermost layer of a film and a polyester polymer layer contg. other spherical inert particles as the other outermost layer.
CONSTITUTION: One outermost layer (A layer) of this polyester film is a polyester polymer layer contg. 0.01-5wt.% spherical inert particles (a) having 0.1-1.0μm volume average particle diameter. The ratio of the major axis size of each of the particles to the minor axis size is 1.0-1.2, the volume average particle diameter is >2 times the number average particle diameter and the relative standard deviation is >0.5. The other outermost layer (B layer) is a polyester polymer layer contg. 0.01-10wt.% spherical inert particles (b) having 0.1-1.0μm volume average particle diameter. The ratio of the major axis size of each of the particles to the minor axis size is 1.0-1.2 and the relative standard deviation is ≤0.5. This polyester film is excellent in flatness, lubricity, scraping resistance, slittability and winding characteristics.
SHIMIZU SHUJI
KATO HIDEKAZU
Next Patent: Grinding equipment