| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyester film almost free from coarse projection and defects, and excellent in surface properties, oligomer deposition-inhibiting properties and productivity. SOLUTION: The polyester composition comprises a 10-30C higher fatty acid component, a 10-30C higher aliphatic alcohol component, or an ester compound thereof in an amount of 0.1-10 wt.% in total and gives measurements of molecular weight polydispersity by the GPC simultaneously satisfying following equations (1) and (2); Mw/Mn>4.4 (1), Mz/Mw>2.0 (2), wherein Mw is a weight-average mol.wt.; Mn is a number-average mol.wt.; and Mz is a z- average mol.wt. The polyester composition gives a polyester film excellent in oligomer deposition-inhibiting properties and is very suitably employed for film applications, as a film for a magnetic tape in particular.
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