| 摘要 |
PURPOSE:To enhance scratch resistance and end surface strength, by a method wherein a polyester composition containing colloidal silica and polyester not containing inorg. particles are respectively set to crystallizing characteristics to be laminated in a specific thickness ratio and the height and interval of the projections on the surface of the polyester composition containing colloidal silica are set to specific ranges. CONSTITUTION:A biaxially oriented polyester film is formed by laminating a composition layer (B-layer) wherein spherical silica caused by colloidal silica is contained in polyester to a polyester layer (A-layer) substantially containing no inorg particles. In this film, the thickness ratio of the A-layer and the B-layer is 0.04-1.4, the difference of a crystallizing parameter DELTATcg between polyester and the composition is 1-45 deg.C, the average projection height on the surface of the composition layer (B-layer) is 20-150nm and the average projection interval on the surface of said layer is 20mum or less. The polyester in both of the polyester layer and the composition contains a principal constitutional component composed of a structural unit selected from an ethylene terephthalate unit, an ethylene alpha, beta-bis (2-chlorophenoxy) ethane-4, 4'-dicarboxylate unit and an ethylene 2, 6-naphthalate unit. |
