| 摘要 |
PROBLEM TO BE SOLVED: To enhance reflectivity and abrasion resistance such that particles do not fall off even by surface rubbing by specifying the surface glossiness of at least the single surface of a polyester film, the concn. of particles in the surface layer thereof and the refractive index in the thickness direction of the polyester film. SOLUTION: The surface glossiness of at least the single surface of a polyester film is set to 5-80% and the concn. of particles in the surface layer thereof is set to 0.5wt.% or less and the refractive index in the thickness direction of the polyester film is set to 1.46-1.54. Therefore, pellets of high speed crystallizing polyester A are dried to be supplied to a known melt extruder. Then, polyester A is laminated to at least the single surface of polyester B by using a two-or three-layered manifold or confluent block and a two-or three-layered sheet is extruded from a slit like cap and the extrudate is cooled by a casting roll to form a non-stretched film which is, in turn, heat-treated to be stretched. |
